Electrophotographic light-sensitive material

ABSTRACT

An electrophotographic light-sensitive material comprising a support having provided thereon at least one photoconductive layer containing an inorganic photoconductive substance and a binder resin, wherein the binder resin comprises (A) at least one resin (resin (A)) having a weight average molecular weight of from 1×10 3  to 2×10 4  and containing not less than 30% by weight of a polymer component corresponding to a repeating unit represented by the general formula (I) described below, and having at least one specified acidic group bonded to one of the terminals of the main chain thereof: ##STR1## wherein a 1 , a 2  and R 1  are as defined in the specification; and (B) at least one graft type copolymer (resin (B)) having a weight average molecular weight of from 3×10 4  to 1×10 6  and formed from, as a copolymerizable component, at least one mono-functional macromonomer (M) having a weight average molecular weight of from 1×10 3  to 2×10 4  and comprising an AB block copolymer being composed of an A block comprising at least one polymer component containing at least one specified acidic group, and a B block containing at least one polymer component represented by the general formula (II) described below and having a polymerizable double bond group bonded to the terminal of the main chain of the B block polymer: ##STR2## wherein b 1 , b 2 , X 1  and R 21  are as defined in the specification. 
     The electrophotographic light-sensitive material exhibits excellent electrostatic characteristics and mechanical strength even under severe conditions. Also, it is advantageously employed in the scanning exposure system using a semiconductor laser beam.

FIELD OF THE INVENTION

The present invention relates to an electrophotographic light-sensitivematerial, and more particularly to an electrophotographiclight-sensitive material which is excellent in electrostaticcharacteristics and moisture resistance.

BACKGROUND OF THE INVENTION

An electrophotographic light-sensitive material may have variousstructures depending upon the characteristics required or anelectrophotographic process to be employed.

An electrophotographic system in which the light-sensitive materialcomprises a support having thereon at least one photoconductive layerand, if necessary, an insulating layer on the surface thereof is widelyemployed. The electrophotographic light-sensitive material comprising asupport and at least one photoconductive layer formed thereon is usedfor the image formation by an ordinary electrophotographic processincluding electrostatic charging, imagewise exposure, development, and,if desired, transfer.

Furthermore, a process using an electrophotographic light-sensitivematerial as an offset master plate precursor for direct plate making iswidely practiced. Particularly, a printing system using a directelectrophotographic printing plate has recently become important forproviding high quality prints of from several hundreds to severalthousands.

Binders which are used for forming the photoconductive layer of anelectrophotographic light-sensitive material are required to beexcellent in the film-forming properties by themselves and thecapability of dispersing photoconductive powder therein. Also, thephotoconductive layer formed using the binder is required to havesatisfactory adhesion to a base material or support. Further, thephotoconductive layer formed by using the binder is required to havevarious excellent electrostatic characteristics such as high chargingcapacity, small dark decay, large light decay, and less fatigue due toprior light-exposure and also have an excellent image formingproperties, and the photoconductive layer stably maintains theseelectrostatic characteristics regardless of change of humidity at thetime of image formation.

Further, extensive investigations have been made on lithographicprinting plate precursors using an electrophotographic light-sensitivematerial, and for such a purpose, binder resins for a photoconductivelayer which satisfy both the electrostatic characteristics as anelectrophotographic light-sensitive material and printing properties asa printing plate precursor are required.

However, conventional binder resins used for electrophotographiclight-sensitive materials have various problems particularly inelectrostatic characteristics such as a charging property, dark chargeretention and photosensitivity, and smoothness of the photoconductivelayer.

In order to overcome these problems, JP-A-63-217354 and JP-A-1-70761(the term "JP-A" as used herein means an "unexamined Japanese patentapplication") disclose improvements in the smoothness of thephotoconductive layer and electrostatic characteristics by using, as abinder resin, a resin having a weight average molecular weight of from1×10³ to 1×10⁴ and containing at random an acidic group in a side chainof the polymer or a resin having a weight average molecular weight offrom 1×10³ to 5×10⁵ and having an acidic group bonded at only oneterminal of the polymer main chain thereby obtaining an image having nobackground stains.

Also, JP-A-1-100554 and JP-A-1-214865 disclose a technique using, as abinder resin, a resin containing an acidic group in a side chain of thecopolymer or at the terminal of the polymer main chain, and containing apolymerizable component having a heat- and/or photo-curable functionalgroup; JP-A-1-102573 and JP-A-2-874 disclose a technique using a resincontaining an acidic group in a side chain of the copolymer or at theterminal of the polymer main chain, and a crosslinking agent incombination; JP-A-64-564, JP-A-63-220149, JP-A-63-220148, JP-A-1-280761,JP-A-1-116643 and JP-A-1-169455 disclose a technique using a resinhaving a low molecular weight (a weight average molecular weight of from1×10³ to 1×10⁴) and a resin having a high molecular weight (a weightaverage molecular weight of 1×10⁴ or more) in combination; andJP-A-1-211766 and JP-A-2-34859 disclose a technique using the above lowmolecular weight resin and a heat- and/or photo-curable resin incombination. These references disclose that, according to the proposedtechniques, the film strength of the photoconductive layer can beincreased sufficiently and also the mechanical strength of thelight-sensitive material can be increased without adversely affectingthe above-described electrostatic characteristics achieved by using aresin containing an acidic group in a side chain or at the terminal ofthe polymer main chain.

On the other hand, in order to evaluate electrostatic characteristics ofelectrophotographic light-sensitive materials, values of E_(1/2) andE_(1/10) which are obtained based on exposure amounts corresponding totimes required for decay the surface potential to 1/2 and 1/10,respectively are conventionally employed. These two values are importantfactors for evaluating reproducibility of original in practical imageformation. More specifically, as the values of E_(1/2) and E_(1/10) aresmall and a difference thereof is small, clear duplicated images withoutblur can be reproduced.

In addition, another point at the image formation is a degree ofelectrical potential remaining in the exposed area (non-image area)after light exposure. When the degree of remaining electrical potentialis high at the image formation, background fog is formed in thenon-image area of duplicated images. An electrostatic characteristicsmainly corresponding to this subject is a value of E_(1/100). Thesmaller the value, the better the image forming performance.

In particular, in a recent scanning exposure system using asemiconductor laser beam, the value of E_(1/100) becomes an importantfactor in addition to the charging property (V₁₀), dark decay retentionrate (DRR) and E_(1/10) conventionally employed, since there is therestriction on the power of laser beam.

In case of using a resin having a low molecular weight and containing anacidic group and a resin having a high molecular weight or a heat-and/or photo-curable resin in combination as above described knowntechniques, the V₁₀, DRR and E_(1/10) are reached to a substantiallysatisfactory level. However, it has been found that the value ofE_(1/100) obtained in the case of changing the environmental conditionsor in the case of using a laser beam of low power is not sufficient andbackground fog occurs in duplicated images.

SUMMARY OF THE INVENTION

The present invention has been made for solving the problems ofconventional electrophotographic light-sensitive materials as describedabove and meeting the requirement for the light-sensitive materials.

An object of the present invention is to provide an electrophotographiclight-sensitive material having stable and excellent electrostaticcharacteristics and giving clear good images even when the environmentalconditions at the formation of duplicated images are changed to alow-temperature and low-humidity or to high-temperature andhigh-humidity.

Another object of the present invention is to provide a CPCelectrophotographic light-sensitive material having excellentelectrostatic characteristics and showing less environmental dependency.

A further object of the present invention is to provide anelectrophotographic light-sensitive material effective for a scanningexposure system using a semiconductor laser beam.

A still further object of this invention is to provide anelectrophotographic lithographic printing plate precursor formingneither background stains nor edge marks of originals pasted up on theprints.

Other objects of the present invention will become apparent from thefollowing description and examples.

It has been found that the above described objects of the presentinvention are accomplished by an electrophotographic light-sensitivematerial comprising a support having provided thereon at least onephotoconductive layer containing an inorganic photoconductive substanceand a binder resin, wherein the binder resin comprises (A) at least oneresin (resin (A)) having a weight average molecular weight of from 1×10³to 2×10⁴ and containing not less than 30% by weight of a polymercomponent corresponding to a repeating unit represented by the generalformula (I) described below, and having at least one acidic groupselected from the group consisting of --PO₃ H₂, --SO₃ H, --COOH, --OH,##STR3## (wherein R represents a hydrocarbon group or --OR' (wherein R'represents a hydrocarbon group)) and a cyclic acid anhydride-containinggroup bonded to one of the terminals of the main chain thereof; ##STR4##wherein a₁ and a₂ each represents a hydrogen atom, a halogen atom, acyano group or a hydrocarbon group; and R₁ represents a hydrocarbongroup; and (B) at least one graft type copolymer (resin (B)) having aweight average molecular weight of from 3×10⁴ to 1×10⁶ and formed from,as a copolymerizable component, at least one mono-functionalmacromonomer (M) having a weight average molecular weight of from 1×10³to 2×10⁴ and comprising an AB block copolymer being composed of an Ablock comprising at least one polymer component containing at least oneacidic group selected from --PO₃ H₂, --COOH, --SO₃ H, a phenolic hydroxygroup, ##STR5## (wherein R represents a hydrocarbon group or --OR'(wherein R'represents a hydrocarbon group)) and a cyclic acidanhydride-containing group, and a B block containing at least onepolymer component represented by the general formula (II) describedbelow and having a polymerizable double bond group bonded to theterminal of the main chain of the B block polymer. ##STR6## wherein b₁and b₂ each represents a hydrogen atom, a halogen atom, a cyano group, ahydrocarbon group, --COOR₂₄ or --COOR₂₄ bonded via a hydrocarbon group(wherein R₂₄ represents a hydrocarbon group); X₁ represents --COO--,--OCO--, --CH₂)_(l1) OCO--, --CH₂)_(l2) COO-- (wherein l₁ and l₂ eachrepresents an integer of from 1 to 3), --O--, --SO₂ --, --CO--, ##STR7##(wherein R₂₃ represent a hydrogen atom or a hydrocarbon group),--CONHCOO--, --CONHCONH--, or ##STR8## and R₂₁ represents a hydrocarbongroup, provided that when X₁ represents ##STR9## R₂₁ represents ahydrogen atom or a hydrocarbon group.

DETAILED DESCRIPTION OF THE INVENTION

The binder resin which can be used in the present invention comprises atleast (A) a low-molecular weight resin (hereinafter referred to as resin(A)) containing the copolymer component having the specific repeatingunit and having the acidic group (the term "acidic group" as used hereinmeans and includes a cyclic acid anhydride-containing group, unlessotherwise indicated) at one of the terminals of the main chain thereofand (B) a high-molecular weight resin (hereinafter referred to as resin(B)) composed of a graft type copolymer formed from, as acopolymerizable component, at least one mono-functional macromonomer (M)comprising an AB block copolymer being composed of an A block comprisinga polymer component containing the specific acidic group described aboveand a B block comprising a polymer component represented by the generalformula (II) described above and having a polymerizable double bondgroup bonded to the terminal of the main chain of the B block polymer.

According to a preferred embodiment of the present invention, the lowmolecular weight resin (A) is a low molecular weight resin (hereinafterreferred to as resin (A')) having an acidic group bonded to the terminalof the polymer main chain thereof and containing a methacrylatecomponent having a specific substituent containing a benzene ring whichhas a specific substituent(s) at the 2-position or 2- and 6-positionsthereof or a specific substituent containing an unsubstitutednaphthalene ring represented by the following general formula (Ia) or(Ib): ##STR10## wherein A₁ and A₂ each represents a hydrogen atom, ahydrocarbon group having from 1 to 10 carbon atoms, a chlorine atom, abromine atom, --COD₁ or --COOD₂, wherein D₁ and D₂ each represents ahydrocarbon group having from 1 to 10 carbon atoms; and B₁ and B₂ eachrepresents a mere bond or a linking group containing from 1 to 4 linkingatoms, which connects --COO-- and the benzene ring.

According to another preferred embodiment of the present invention, thehigh molecular weight resin (B) is a graft type copolymer containing atleast one macromonomer (M) described above and a polymer componentrepresented by the following general formula (III): ##STR11## whereinb₃, b₄, X₂ and R₂₂ each has the same meaning as defined for b₁, b₂, X₁and R₂₁.

In the present invention, the acidic group bonded to the terminal of thepolymer main chain of the resin (A) of a low molecular weight whichcontains the specific copolymer component is adsorbed ontostoichiometrical defects of an inorganic photoconductive substance, andthe resin has a function to improve covering power for thephotoconductive substance due to its low molecular weight, tosufficiently cover the surface thereof, whereby electron traps of thephotoconductive substance can be compensated for and humidity resistancecan be greatly improved, while assisting the photoconductive substanceto be sufficiently dispersed without agglomeration. On the other hand,the resin (B) not only serves to sufficiently heighten the mechanicalstrength of a photoconductive layer, which may be insufficient in caseof using the resin (A) alone, without damaging the excellentelectrophotographic characteristics attained by the use of the resin(A), but also provides sufficiently high image forming performance inthe case of changing the environmental conditions or in the case ofusing a laser beam of small power.

It is believed that the excellent characteristics of theelectrophotographic light-sensitive material can be obtained byemploying the resin (A) and the resin (B) as binder resins for inorganicphotoconductive substance, wherein the weight average molecular weightof the resins and the content and position of the acidic group thereinare specified, whereby the strength of interactions between theinorganic photoconductive substance and the resins can be appropriatelycontrolled. More specifically, it is believed that theelectrophotographic characteristics and mechanical strength of the layeras described above can be greatly improved by the fact that the resin(A) having a relatively strong interaction to the inorganicphotoconductive substance selectively adsorbes thereon; whereas, in theresin (B) which has a weak activity compared with the resin (A), theacidic group bonded to the specific position to the polymer main chainthereof mildly interacts with the inorganic photoconductive substance toa degree which does not damage the electrophotographic characteristics,and the long main molecular chain and the molecular chains of the graftportion mutually interact between the resins (B).

In case of using the resin (A'), the electrophotographiccharacteristics, particularly, V₁₀, DRR and E_(1/10) of theelectrophotographic material can be furthermore improved as comparedwith the use of the resin (A). While the reason of this fact is notfully clear, it is believed that the polymer molecular chain of theresin (A') suitably arranges on the surface of inorganic photoconductivesubstance such as zinc oxide in the layer depending on the plane effectof the benzene ring having a substituent at the ortho position or thenaphthalene ring which is an ester component of the methacrylate wherebythe above described improvement is achieved.

Further, according to the present invention, the smoothness of thephotoconductive layer is improved.

On the contrary, when an electrophotographic light-sensitive materialhaving a photoconductive layer with a rough surface is used as anelectrophotographic lithographic printing plate precurser, thedispersion state of inorganic particles as photoconductive substance anda binder resin is improper and thus a photoconductive layer is formed ina state containing aggregates of the photoconductive substance, wherebythe surface of the non-image portions of the photoconductive layer isnot uniformly and sufficiently rendered hydrophilic by applying theretoan oil-desensitizing treatment with an oil-desensitizing solution tocause attaching of printing ink at printing, which results in theformation of background stains in the non-image portions of theresulting prints.

According to the present invention, the interaction of adsorption andcovering between the inorganic photoconductive substance and the binderresins is suitably performed, and the sufficient mechanical strength ofthe photoconductive layer is achieved by the combination of the resinsdescribed above.

In the resin (A), the weight average molecular weight is suitably from1×10³ to 2×10⁴, preferably from 3×10³ to 1×10⁴, the content of thecopolymerizable component corresponding to the repeating unitrepresented by the general formula (I) is suitably not less than 30% byweight, preferably from 50 to 97% by weight, and the content of theacidic group bonded to the terminal of the polymer main chain issuitably from 0.5 to 15% by weight, preferably from 1 to 10% by weight.

In the resin (A'), the content of the methacrylate copolymer componentcorresponding to the repeating unit represented by the general formula(Ia) or (Ib) is suitably not less than 30% by weight, preferably from 50to 97% by weight, and the content of the acidic group bonded to theterminal of the polymer main chain is suitably from 0.5 to 15% byweight, preferably from 1 to 10% by weight.

The glass transition point of the resin (A) is preferably from -20° C.to 110° C., and more preferably from -10° C. to 90° C.

On the other hand, the weight average molecular weight of the resin (B)is suitably from 3×10⁴ to 1×10⁶, preferably from 5×10⁴ to 5×10⁵.

The glass transition point of the resin (B) is preferably from 0° C. to110° C., and more preferably from 20° C. to 90° C.

The content of the mono-functional macromonomer comprising an AB blockcopolymer component in the resin (B) is preferably from 1 to 60% byweight, more preferably from 5 to 50% by weight.

If the molecular weight of the resin (A) is less than 1×10³, thefilm-forming ability thereof is undesirably reduced, whereby thephotoconductive layer formed cannot keep a sufficient film strength,while if the molecular weight thereof is larger than 2×10⁴, thefluctuations of electrophotographic characteristics (in particular, darkdecay retention rate and photosensitivity of E_(1/10)) of thephotoconductive layer containing a spectral sensitizing dye for thesensitization in the range of from near-infrared to infrared becomesomewhat large and thus the effect for obtaining stable duplicate imagesaccording to the invention is reduced under severe conditions of hightemperature and high humidity or low temperature and low humidity.

If the content of the acidic group in the resin (A) is less than 0.5% byweight, the resulting electrophotographic light-sensitive material hasan initial potential too low to provide a sufficient image density. If,on the other hand, it is more than 15% by weight, dispersibility of thephotoconductive substance is reduced, the smoothness of thephotoconductive layer and the electrophotographic characteristicsthereof under a high humidity condition are deteriorated. Further,background stains are increased when it is used as a offset master.

If the molecular weight of the resin (B) is less than 3×10⁴, asufficient film strength may not be maintained. On the other hand, isthe molecular weight thereof is larger than 1×10⁶, the dispersibility ofthe photoconductive substance is reduced, the smoothness of thephotoconductive layer is deteriorated, and image quality of duplicatedimages (particularly reproducibility of fine lines and letters) isdegradated. Further, the background stains are increased in case ofusing it as an offset master.

Further, if the content of the macromonomer is less than 1% by weight inthe resin (B), electrophotographic characteristics (particularly darkdecay retention rate and photosensitivity) may be reduced and thefluctuations of electrophotographic characteristics of thephotoconductive layer, particularly that containing a spectralsensitizing dye for the sensitization in the range of from near-infraredto infrared become large under severe conditions. The reason therefor isconsidered that the construction of the polymer becomes similar to thatof a conventional homopolymer or random copolymer resulting from theslight amount of macromonomer portion present therein to constitute thegraft part.

On the other hand, if the content of the macromonomer is more than 60%by weight, the copolymerizability of the macromonomer with othermonomers corresponding to other copolymerizable components may becomeinsufficient, and the sufficient electrophotographic characteristics cannot be obtained as the binder resin.

Now, the resin (A) which can be used in the present invention will beexplained in detail below.

The resin (A) used in the present invention contains at least onerepeating unit represented by the general formula (I) as acopolymerizable component as described above.

In the general formula (I), a₁ and a₂ each represents a hydrogen atom, ahalogen atom (e.g., chlorine and bromine), a cyano group or ahydrocarbon group, preferably an alkyl group having from 1 to 4 carbonatoms (e.g., methyl, ethyl, propyl and butyl); and R₁ represents ahydrocarbon group, preferably a substituted or unsubstituted alkyl grouphaving from 1 to 18 carbon atoms (e.g., methyl, ethyl, propyl, butyl,pentyl, hexyl, octyl, decyl, dodecyl, tridecyl, tetradecyl,2-chloroethyl, 2-bromoethyl, 2-cyanoethyl, 2-hydroxyethyl,2-methoxyethyl, 2-ethoxyethyl, and 3-hydroxypropyl), a substituted orunsubstituted alkenyl group having from 2 to 18 carbon atoms (e.g.,vinyl, allyl, isopropenyl, butenyl, hexenyl, heptentyl, and octenyl), asubstituted or unsubstituted aralkyl group having from 7 to 12 carbonatoms (e.g., benzyl, phenethyl, naphthylmethyl, 2-naphthylethyl,methoxybenzyl, ethoxybenzyl, and methylbenzyl), a substituted orunsubstituted cycloalkyl group having from 5 to 8 carbon atoms (e.g.,cyclopentyl, cyclohexyl, and cycloheptyl), or a substituted orunsubstituted aryl group (e.g., phenyl, tolyl, xylyl, mesityl, naphthyl,methoxyphenyl, ethoxyphenyl, fluorophenyl, difluorophenyl, bromophenyl,chlorophenyl, dichlorophenyl, iodophenyl, methoxycarbonylphenyl,ethoxycarbonylphenyl, cyanophenyl, and nitrophenyl).

More preferably, the copolymer component corresponding to the repeatingunit represented by the general formula (I) is a methacrylate componenthaving the specific aryl group represented by the following generalformula (Ia) or (Ib): ##STR12## wherein A₁ and A₂ each represents ahydrogen atom, a hydrocarbon group having from 1 to 10 carbon atoms, achlorine atom, a bromine atom, --COD₁ or --COOD₂, wherein D₁ and D₂ eachrepresents a hydrocarbon group having from 1 to 10 Carbon atoms; and B₁and B₂ each represents a mere bond or a linking group containing from 1to 4 linking atoms, which connects --COO-- and the benzene

In the general formula (Ia), A₁ and A₂ each preferably represents ahydrogen atom, a chlorine atom, a bromine atom, an alkyl group havingfrom 1 to 4 carbon atoms (e.g., methyl, ethyl, propyl, and butyl), anaralkyl group having from 7 to 9 carbon atoms (e.g., benzyl, phenethyl,3-phenylpropyl, chlorobenzyl, dichlorobenzyl, bromobenzyl, methylbenzyl,methoxybenzyl, and chloromethylbenzyl), an aryl group (e.g., phenyl,tolyl, xylyl, bromophenyl, methoxyphenyl, chlorophenyl, anddichlorophenyl), --COD₁ or --COOD₂, wherein D₁ and D₂ each preferablyrepresents any of the above-recited hydrocarbon groups).

In the general formula (Ia), B₁ is a mere bond or a linking groupcontaining from 1 to 4 linking atoms, e.g , --CH₂ --_(n).sbsb.1 (n₁represents an integer of 1, 2 or 3), --CH₂ OCO--, --CH₂ CH₂ OCO--, --CH₂O--_(n).sbsb.2 (n₂ represents an integer of 1 or 2), and --CH₂ CH₂ O--,which connects --COO-- and the benzene ring.

In the general formula (Ib), B₂ has the same meaning as B₁ in thegeneral formula (Ia).

Specific examples of the copolymer component corresponding to therepeating unit represented by the general formula (Ia) or (Ib) which canbe used in the resin (A') according to the present invention are setforth below, but the present invention should not be construed as beinglimited thereto. In the following formulae, T₁ and T₂ each representsCl, Br or I; R₁₁ represents ##STR13## a represents an integer of from 1to 4; b represents an integer of from 0 to 3; and c represents aninteger of from 1 to 3. ##STR14##

The acidic group which is bonded to one of the terminals of the polymermain chain in the resin (A) according to the present inventionpreferably includes --PO₃ H₂, --SO₃ H, --COOH, ##STR15## (wherein R isas defined above), and a cyclic acid anhydride-containing group.

In the acidic group ##STR16## above, R represents a hydrocarbon group or--OR', wherein R' represents a hydrocarbon group. The hydrocarbon grouprepresented by R or R' preferably includes an aliphatic group havingfrom 1 to 22 carbon atoms (e.g., methyl, ethyl, propyl, butyl, hexyl,octyl, decyl, dodecyl, octadecyl, 2-chloroethyl, 2-methoxyethyl,3-ethoxypropyl, allyl, crotonyl, butenyl, cyclohexyl, benzyl, phenethyl,3-phenylpropyl, methylbenzyl, chlorobenzyl, fluorobenzyl, andmethoxybenzyl) and a substituted or unsubstituted aryl group (e.g.,phenyl, tolyl, ethylphenyl, propylphenyl, chlorophenyl, fluorophenyl,bromophenyl, chloromethylphenyl, dichlorophenyl, methoxyphenyl,cyanophenyl, acetamidophenyl, acetylphenyl, and butoxyphenyl).

The cyclic acid anhydride-containing group is a group containing atleast one cyclic acid anhydride. The cyclic acid anhydride to becontained includes an aliphatic dicarboxylic acid anhydride and anaromatic dicarboxylic acid anhydride.

Specific examples of the aliphatic dicarboxylic acid anhydrides includesuccinic anhydride ring, glutaconic anhydride ring, maleic anhydridering, cyclopentane-1,2-dicarboxylic acid anhydride ring,cyclohexane-1,2-dicarboxylic acid anhydride ring,cyclohexene-1,2-dicarboxylic acid anhydride ring, and2,3-bicyclo[2,2,2]octanedicarboxylic acid anhydride. These rings may besubstituted with, for example, a halogen atom (e.g., chlorine andbromine) and an alkyl group (e.g., methyl, ethyl, butyl, and hexyl).

Specific examples of the aromatic dicarboxylic acid anhydrides includephthalic anhydride ring, naphtnalene-dicarboxylic acid anhydride ring,pyridinedicarboxylic acid anhydride ring and thiophenedicarboxylic acidanhydride ring. These rings may be substituted with, for example, ahalogen atom (e.g., chlorine and bromine), an alkyl group (e.g., methyl,ethyl, propyl, and butyl), a hydroxyl group, a cyano group, a nitrogroup, and an alkoxycarbonyl group (e.g., methoxycarbonyl andethoxycarbonyl).

Compounds containing --OH group include alcohols containing a vinylgroup or an allyl group (e.g., allyl alcohol, methacrylates containing--OH group in an ester substituent thereof, and arylamides containing--OH group in an N-substituent thereof), hydroxyphenol, andmethacrylates and amides containing a hydroxyphenyl group as asubstituent.

The above-described acidic group may be bonded to one of the polymermain chain terminals either directly or via an appropriate linkinggroup.

The linking group can be any group for connecting the acidic group tothe polymer main chain terminal. Specific examples of suitable linkinggroup include ##STR17## (wherein d₁ and d₂, which may be the same ordifferent, each represents a hydrogen atom, a halogen atom (e.g.,chlorine, and bromine), a hydroxyl group, a cyano group, an alkyl group(e.g., methyl, ethyl, 2-chloroethyl, 2-hydroxyethyl, propyl, butyl, andhexyl), an aralkyl group (e.g., benzyl, and phenethyl), an aryl group(e.g., phenyl)), ##STR18## (wherein d₃ and d₄ each has the same meaningas defined for d₁ or d₂ above), ##STR19## (wherein d₅ represents ahydrogen atom or a hydrocarbon group preferably having from 1 to 12carbon atoms (e.g., methyl, ethyl, propyl, butyl, hexyl, octyl, decyl,dodecyl, 2-methoxyethyl, 2-chloroethyl, 2-cyanoethyl, benzyl,methylbenzyl, chlorobenzyl, methoxybenzyl, phenethyl, phenyl, tolyl,chlorophenyl, methoxyphenyl, and butylphenyl)), --CO--, --COO--,--OCO--, ##STR20## --SO₂ --, --NHCONH--, --NHCOO--, --NHSO₂ --,--CONHCOO--, --CONHCONH--, a heterocyclic ring, preferably a 5-memberedor 6-membered ring containing at least one of an oxygen atom, a sulfuratom and a nitrogen atom as a hetero atom or a condensed ring thereof(e.g., thiophene, pyridine, furan, imidazole, piperidine, andmorpholine), ##STR21## (wherein d₆ and d₇, which may be the same ordifferent, each represents a hydrocarbon group or --Od₈ (wherein d₈represents a hydrocarbon group)), and a combination thereof. Suitableexample of the hydrocarbon group represented by d₆, d₇ or d₈ includethose described for d₅.

Moreover, the binder resin (A) preferably contains from 1 to 20% byweight of a copolymerizable component having a heat- and/orphoto-curable functional group in addition to the copolymerizablecomponent represented by the general formula (I) (including thatrepresented by the general formula (Ia) or (Ib)) described above, inview of achieving higher mechanical strength.

The term "heat- and/or photo-curable functional group" as used hereinmeans a functional group capable of inducing curing reaction of a resinon application of at least one of heat and light.

Specific examples of the photo-curable functional group include thoseused in conventional light-sensitive resins known as photocurable resinsas described, for example, in Hideo Inui and Gentaro Nagamatsu, KankoseiKobunshi, Kodansha (1977), Takahiro Tsunoda, Shin-Kankosei Jushi,Insatsu Gakkai Shuppanbu (1981), G. E. Green and B. P. Strak, J. Macro.Sci. Reas. Macro. Chem., C 21 (2), pp. 187 to 273 (1981-82), and C. G.Rattey, Photopolymerization of Surface Coatings, A Wiley IntersciencePub. (1982).

The heat-curable functional group which can be used includes functionalgroups excluding the above-specified acidic groups. Examples of theheat-curable functional groups are described, for example, in TsuyoshiEndo, Netsukokasei Kobunshi no Seimitsuka, C. M. C. (1986), YujiHarasaki, Saishin Binder Gijutsu Binran, Chapter II-I, Sogo GijutsuCenter (1985), Takayuki Ohtsu, Acryl Jushi no Gosei Sekkei toShin-Yotokaihatsu, Chubu Kei-ei Kaihatsu Center Shuppanbu (1985), andEizo Ohmori, Kinosei Acryl Kei Jushi, Techno System (1985).

Specific examples of the heat-curable functional group which can usedinclude --OH, --SH, --NH₂, --NHR₃ (wherein R₃ represents a hydrocarbongroup, for example, a substituted or unsubstituted alkyl group havingfrom 1 to 10 carbon atoms (e.g., methyl, ethyl, propyl, butyl, hexyl,octyl, decyl, 2-chloroethyl, 2-methoxyethyl, and 2-cyanoethyl), asubstituted or unsubstituted cycloalkyl group having from 4 to 8 carbonatoms (e.g., cycloheptyl and cyclohexyl), a substituted or unsubstitutedaralkyl group having from 7 to 12 carbon atoms (e.g., benzyl, phenethyl,3-phenylpropyl, chlorobenzyl, methylbenzyl, and methoxybenzyl), and asubstituted or unsubstituted aryl group (e.g., phenyl, tolyl, xylyl,chlorophenyl, bromophenyl, methoxyphenyl, and naphthyl)), ##STR22##(wherein R₄ represents a hydrogen atom or an alkyl group having from 1to 8 carbon atoms (e.g., methyl, ethyl, propyl, butyl, hexyl, andoctyl)), ##STR23## (wherein e₁ and e₂ each represents a hydrogen atom, ahalogen atom (e.g., chlorine and bromine) or an alkyl group having from1 to 4 carbon atoms (e.g., methyl and ethyl)).

Other examples of the functional group include polymerizable double bondgroups, for example, ##STR24##

In order to introduce at least one functional group selected from theheat- and/or photo-curable functional groups into the binder resinaccording to the present invention, a method comprising introducing thefunctional group into a polymer by high molecular reaction or a methodcomprising copolymerizing at least one monomer containing at least oneof the functional groups with a monomer corresponding to the repeatingunit of the general formula (I) (including that of the general formula(Ia) or (Ib)) can be employed.

The above-described high molecular reaction can be carried out by usingconventionally known low molecular synthesis reactions. For the details,reference can be made to, e.g., Nippon Kagakukai (ed.), Shin-JikkenKaguku Koza, Vol. 14, Yuki Kagobutsu no Gosei to Hanno (I) to (V),Maruzen K.K. and Yoshio Iwakura and Keisuke Kurita, Hannosei Kobunshi.

Suitable examples of the monomers containing the functional groupcapable of inducing heat- and/or photo-curable reaction include vinylcompounds which are copolymerizable with the monomers corresponding tothe repeating unit of the general formula (I) and contain theabove-described functional group. More specifically, compounds similarto those described in detail hereinafter as the acidic group-containingcomponents for the macromonomer (M) which contain further theabove-described functional group in their substituent are illustrated.

Specific examples of the heat- and/or photo-curable functionalgroup-containing repeating unit are set forth below, but the presentinvention should not be construed as being limited thereto. In thefollowing formulae, R₁₁ and a each has the same meaning as definedabove; P₁ and P₂ each represents --H or --CH₃ ; R₁₂ represents --CH═CH₂or --CH₂ CH═CH₂ ; R₁₃ represents --CH═CH₂, ##STR25## or --CH═CHCH₃ ; R₁₄represents --CH═CH₂, --CH₂ CH═CH₂, ##STR26## Z represents S or O; T₃represents --OH or --NH₂ ; d represents an integer of from 2 to 11; erepresents an integer of from 1 to 11; f represents an integer of from 1to 11; and g represents an integer of from 1 to 10. ##STR27##

The resin (A) according to the present invention may further compriseother monomers as copolymer components in addition to the monomercorresponding to the repeating unit of the general formula (I)(including that of the general formula (Ia) or (Ib)), and, if desired,the heat- and/or photo-curable functional group-containing monomer.Examples of such monomers include, in addition to methacrylic acidesters, acrylic acid esters and crotonic acid esters other than thoserepresented by the general formula (I), α-olefins, vinyl or allyl estersof carboxylic acids (including, e.g., acetic acid, propionic acid,butyric acid, and valeric acid, as examples of the carboxylic acids),acrylonitrile, methacrylonitrile, vinyl ethers, itaconic acid esters(e.g., dimethyl itaconate, and diethyl itaconate), acrylamides,methacrylamides, styrenes (e.g., styrene, vinyltoluene, chlorostyrene,hydroxystyrene, N,N-dimethylaminomethylstyrene, methoxycarbonylstyrene,methanesulfonyloxystyrene, and vinylnaphthalene), and heterocyclic vinylcompounds (e.g., vinylpyrrolidone, vinylpyridine, vinylimidazole,vinylthiophene, vinylimidazoline, vinylpyrazoles, vinyldioxane,vinylquinoline, vinyltetrazole, and vinyloxazine).

In such a case, the content of the other copolymer monomers in the resin(A) is preferably not more than 30% by weight.

The resin (A) according to the present invention, in which the specificacidic group is bonded to only one terminal of the polymer main chain,can easily be prepared by an ion polymerization process, in which avarious kind of a reagent is reacted at the terminal of a living polymerobtained by conventionally known anion polymerization or cationpolymerization; a radical polymerization process, in which radicalpolymerization is performed in the presence of a polymerizationinitiator and/or a chain transfer agent which contains the specificacidic group in the molecule thereof; or a process, in which a polymerhaving a reactive group (for example, an amino group, a halogen atom, anepoxy group, and an acid halide group) at the terminal obtained by theabove-described ion polymerization or radical polymerization issubjected to a high molecular reaction to convert the terminal reactivegroup to the specific acidic group.

For the details, reference can be made to, e.g., P. Dreyfuss and R. P.Quirk, Encycl. Polym. Sci. Eng., Vol. 7, p. 551 (1987), Yoshiki Nakajoand Yuya Yamashita, Senryo to Yakuhin, Vol. 30, p. 232 (1985), AkiraUeda and Susumu Nagai, Kagaku to Kogyo, Vol. 60, p. 57 (1986) andliterature references cited therein.

Specific examples of the chain transfer agent to be used includemercapto compounds containing the acidic group or the reactive groupcapable of being converted to the acidic group (e.g., thioglycolic acid,thiomalic acid, thiosalicyclic acid, 2-mercaptopropionic acid,3-mercaptopropionic acid, 3-mercaptobutyric acid,N-(2-mercaptopropionyl)glycine, 2-mercaptonicotinic acid,3-[N-(2-mercaptoethyl)carbamoyl]propionic acid,3-[N-(2-mercaptoethyl)amino]propionic acid,N-(3-mercaptopropionyl)alanine, 2-mercaptoethanesulfonic acid,3-mercaptopropanesulfonic acid, 4-mecaptobutanesulfonic acid,2-mercaptoethanol, 3-mercapto-1,2-propanediol, 1-mercapto-2-propanol,3-mercapto-2-butanol, mercaptophenol, 2-mercaptoethylamine,2-mercaptoimidazole, 2-mercapto-3-pyridinol,4-(2-mercaptoethyloxycarbonyl) phthalic anhydride,2-mercaptoethylphosphonic acid, and monomethyl2-mercaptoethylphosphonate), and alkyl iodide compounds containing theacidic group or the acidic group-forming reactive group (e.g.,iodoacetic acid, iodopropionic acid, 2-iodoethanol, 2-iodoethanesulfonicacid, and 3-iodopropanesulfonic acid). Preferred of them are mercaptocompounds.

Specific examples of the polymerization initiators containing the acidicgroup or the reactive group include 4,4'-azobis(4-cyanovaleric acid),4,4'-azobis(4-cyanovaleric acid chloride), 2,2'-azobis(2-cyanopropanol),2,2'-azobis(2-cyanopentanol),2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide],2,2'-azobis{2-methyl-N-[1,1-bis(hydroxymethyl)-2-hydroxyethyl]propionamide},2,2'-azobis{2-[1-(2-hydroxyethyl)-2-imidazolin-2-yl]propane},2,2'-azobis[2-(2-imidazolin-2-yl)propane], and2,2'-azobis[2-(4,5,6,7-tetrahydro-1H-1,3-diazepin-2-yl)propane].

The chain transfer agent or polymerization initiator is usually used inan amount of from 0.5 to 15 parts by weight, preferably from 2 to 10parts by weight, per 100 parts by weight of the total monomers.

Now, the resin (B) will be described in detail with reference topreferred embodiments below.

The mono-functional macromonomer (M) which can be employed to form theresin (B) according to the present invention is described in greaterdetail below.

The acidic group contained in a component which constitutes the A blockof the macromonomer (M) includes --PO₃ H₂, --COOH, --SO₃ H, a phenolichydroxy group, ##STR28## (R represents a hydrocarbon group or --OR'(wherein R' represents a hydrocarbon group)), and a cyclic acidanhydride-containing group, and the preferred acidic groups are --COOH,--SO₃ H, a phenolic hydroxy group and ##STR29##

The ##STR30## group and the cyclic acid anhydride-containing group eachhas the same meaning as specifically described in the resin (A) above.Also, the compounds containing a phenolic hydroxy group are selectedfrom the compounds containing --OH group as specifically described inthe resin (A) above.

The polymer component containing the specific acidic group may be formedfrom any of acidic group-containing vinyl compounds copolymerizable witha polymerizable component for constituting the B block of themacromonomer (M), for example, a monomer corresponding to the repeatingunit represented by the general formula (I) (including that representedby the general formula (Ia) or (Ib)). Examples of such vinyl compoundsare described, e.g., in Kobunshi Gakkai (ed.), Kobunshi Data Handbook(Kisohen), Baihukan (1986). Specific examples of these vinyl monomersinclude acrylic acid, α- and/or β-substituted acrylic acids (e.g.,α-acetoxy, α-acetoxymethyl, α-(2-amino)methyl, α-chloro, α-bromo,α-fluoro, α-tributylsilyl, α-cyano, β-chloro, β-bromo,α-chloro-β-methoxy, and α, β-dichloro compounds), methacrylic acid,itaconic acid, itaconic half esters, itaconic half amides, crotonicacid, 2-alkenylcarboxylic acids (e.g., 2-pentenoic acid,2-methyl-2-hexenoic acid, 2-octenoic acid, 4-methyl-2-hexenoic acid, and4-ethyl-2-octenoic acid), maleic acid, maleic half esters, maleic halfamides, vinylbenzenecarboxylic acid, vinylbenzenesulfonic acid,vinylsulfonic acid, vinylphosphonic acid, dicarboxylic acid vinyl orallyl half esters, and ester or amide derivatives of these carboxylicacids or sulfonic acids containing the acidic group in the substituentthereof.

Specific examples of the acidic group-containing polymerizablecomponents are set forth below, but the present invention should not beconstrued as being limited thereto. In the following formulae, Q₁represents --H, --CH₃, --Cl, --Br, --CN, --CH₂ COOCH₃ or --CH₂ COOH; Q₂represents --H or --CH₃ ; n represents an integer of from 2 to 18; mrepresents an integer of from 1 to 12; and l represents an integer offrom 1 to 4. ##STR31##

Two or more kinds of the above-described polymerizable components eachcontaining the specific acidic group can be included in the A block. Insuch a case, two or more kinds of these acidic group-containingpolymerizable components may be present in the form of a randomcopolymer or a block copolymer.

Also, other components having no acidic group may be contained in the Ablock, and examples of such components include the componentsrepresented by the general formula (II) described in detail below. Thecontent of the component having no acidic group in the A block ispreferably from 0 to 50% by weight, and more preferably from 0 to 20% byweight. It is most preferred that such a component is not contained inthe A block.

Now, the polymerizable component for constituting the B block in themono-functional macromonomer (M) of the graft type copolymer (resin (B))used in the present invention will be explained in more detail below.

The components constituting the B block in the present invention includeat least a repeating unit represented by the general formula (II)described above.

In the general formula (II), X₁ represents --COO--, --OCO--, --CH₂)_(l1)OCO--, --CH₂)_(l2) COO-- (wherein l₁ and l₂ each represents an integerof from 1 to 3), ##STR32## (wherein R₂₃ represents a hydrogen atom or ahydrocarbon group).

Preferred examples of the hydrocarbon group represented by R₂₃ includean alkyl group having from 1 to 18 carbon atoms which may be substituted(e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl octyl, decyl,dodecyl, hexadecyl, octadecyl, 2-chloroethyl, 2-bromoethyl,2-cyanoethyl, 2-methoxycarbonylethyl, 2-methoxyethyl, and3-bromopropyl), an alkenyl group having from 4 to 18 carbon atoms whichmay be substituted (e.g., 2-methyl-1-porpenyl, 2-butenyl, 2-pentenyl,3-methyl-2-pentenyl, 1-pentenyl, 1-hexenyl, 2-hexenyl, and4-methyl-2-hexenyl), an aralkyl group having from 7 to 12 carbon atomswhich may be substituted (e.g., benzyl, phenethyl, 3-phenylpropyl,naphthylmethyl, 2-naphthylethyl, chlorobenzyl, bromobenzyl,methylbenzyl, ethylbenzyl, methoxybenzyl, dimethylbenzyl, anddimethoxybenzyl), an alicyclic group having from 5 to 8 carbon atomswhich may be substituted (e.g., cyclohexyl, 2-cyclohexylethyl, and2-cyclopentylethyl), and an aromatic group having from 6 to 12 carbonatoms which may be substituted (e.g., phenyl, naphthyl, tolyl, xylyl,propylphenyl, butylphenyl, octylphenyl, dodecylphenyl, methoxyphenyl,ethoxyphenyl, butoxyphenyl, decyloxyphenyl, chlorophenyl,dichlorophenyl, bromophenyl, cyanophenyl, acetylphenyl,methoxycarbonylphenyl, ethoxycarbonylphenyl, butoxycarbonylphenyl,acetamidophenyl, propioamidophenyl, and dodecyloylamidophenyl).

In the general formula (II), R₂₁ ; represents a hydrocarbon group, andpreferred examples thereof include those described for R₂₃. When X₁represents ##STR33## in the general formula (II), R₂₁ represents ahydrogen atom or a hydrocarbon group.

When X₁ represents ##STR34## the benzene ring may further besubstituted. Suitable examples of the substituents include a halogenatom (e.g., chlorine, and bromine), an alkyl group (e.g., methyl, ethyl,propyl, butyl, chloromethyl, and methoxymethyl), and an alkoxy group(e.g., methoxy, ethoxy, propoxy, and butoxy).

In the general formula (II), b₁ and b₂, which may be the same ordifferent, each preferably represents a hydrogen atom, a halogen atom(e.g., chlorine, and bromine), a cyano group, an alkyl group having from1 to 4 carbon atoms (e.g., methyl, ethyl, propyl, and butyl), --COOR₂₄or --COOR₂₄ bonded via a hydrocarbon group, wherein R₂₄ represents ahydrocarbon group (preferably an alkyl group having 1 to 18 carbonatoms, an alkenyl group having 4 to 18 carbon atoms, an aralkyl grouphaving 7 to 12 carbon atoms, an alicyclic group having 5 to 8 carbonatoms or an aryl group having 6 to 12 carbon atoms, each of which may besubstituted). More specifically, the examples of the hydrocarbon groupsare those described for R₂₃ above. The hydrocarbon group via which--COOR₂₄ is bonded includes, for example, a methylene group, an ethylenegroup, and a propylene group.

More preferably, in the general formula (II), X₁ represents --COO--,--OCO--, --CH₂ OCO--, --CH₂ COO--, --O--, --CONH--, --SO₂ NH or##STR35## and b₁ and b₂, which may be the same or different, eachrepresents a hydrogen atom, a methyl group, --COOR₂₄, or --CH₂ COOR₂₄,wherein R₂₄ represents an alkyl group having from 1 to 6 carbon atoms(e.g., methyl, ethyl, propyl, butyl, and hexyl). Most preferably, eitherone of b₁ and b₂ represents a hydrogen atom.

The B block which is constituted separately from the block A which iscomposed of the polymerizable component containing the above-describedspecific acidic group may contain two or more kinds of the repeatingunits represented by the general formula (II) described above and mayfurther be formed of polymerizable components other than these repeatingunits. When the B block having no acidic group contains two or morekinds of the polymerizable components, the polymerizable components maybe contained in the B block in the form of a random copolymer or a blockcopolymer, but are preferably contained at random therein.

As the polymerizable component other than the repeating unitsrepresented by the general formula (II) which are contained in the Bblock together with the polymerizable component(s) selected from therepeating units of the general formula (II), any componentscopolymerizable with the polymerizable component of the repeating unitscan be used.

Suitable examples of monomer corresponding to the repeating unitcopolymerizable with the polymer component represented by the generalformula (II), as a polymerizable component in the B block includeacrylonitrile, methacrylonitrile and heterocyclic vinyl compounds (e.g.,vinylpyridine, vinylimidazole, vinylpyrrolidone, vinylthiophene,vinylpyrazole, vinyldioxane, and vinyloxazine). Such other monomers areemployed in a range of not more than 20 parts by weight per 100 parts byweight of the total polymerizable components in the B block.

Further, it is preferred that the B block does not contain the polymercomponent containing the acidic group which is a component constitutingthe A block.

As described above, the macromonomer (M) to be used in the presentinvention has a structure of the AB block copolymer in which apolymerizable double bond group is bonded to one of the terminals of theB block composed of the polymer component represented by the generalformula (II) and the other terminal thereof is connected to the A blockcomposed of the polymer component containing the acidic group. Thepolymerizable double bond group will be described in detail below.

Suitable examples of the polymerizable double bond group include thoserepresented by the following general formula (IV): ##STR36## wherein X₃has the same meaning as X₁ defined in the general formula (II), and b₅and b₆, which may be the same or different, each has the same meaning asb₁ and b₂ defined in the general formula (II).

Specific examples of the polymerizable double bond group represented bythe general formula (IV) include ##STR37##

The macromonomer (M) used in the present invention has a structure inwhich a polymerizable double bond group preferably represented by thegeneral formula (IV) is bonded to one of the terminals of the B blockeither directly or through an appropriate linking group.

The linking group which can be used includes a carbon-carbon bond(either single bond or double bond), a carbon-hetero atom bond (thehetero atom includes, for example, an oxygen atom, a sulfur atom, anitrogen atom, and a silicon atom), a hetero atom-hetero atom bond, andan appropriate combination thereof.

More specifically, the bond between the polymerizable double bond groupand the terminal of the B block is a mere bond or a linking groupselected from ##STR38## (wherein R₂₅ and R₂₆ each represents a hydrogenatom, a halogen atom (e.g., fluorine, chlorine, and bromine), a cyanogroup, a hydroxyl group, or an alkyl group (e.g., methyl, ethyl, andpropyl)), ##STR39## (wherein R₂₇ and R₂₈ each represents a hydrogen atomor a hydrocarbon group having the same meaning as defined for R₂₁ in thegeneral formula (II) described above), and an appropriate combinationthereof.

If the weight average molecular weight of the macromonomer (M) exceeds2×10⁴, copolymerizability with other monomers is undesirably reduced.If, on the other hand, it is too low, the effect of improvingelectrophotographic characteristics of the light-sensitive layer wouldbe small. Accordingly, the macromonomer (M) preferably has a weightaverage molecular weight of at least 1×10³.

The macromonomer (M) used in the present invention can be produced by aconventionally known synthesis method. More specifically, it can beproduced by the method comprising previously protecting the acidic groupof a monomer corresponding to the polymerizable component having thespecific acidic group to form a functional group, synthesizing an ABblock copolymer by a so-called known living polymerization reaction, forexample, an ion polymerization reaction with an organic metal compound(e.g., alkyl lithiums, lithium diisopropylamide, and alkylmagnesiumhalides) or a hydrogen iodide/iodine system, a photopolymerizationreaction using a porphyrin metal complex as a catalyst, or a grouptransfer polymerization reaction, introducing a polymerizable doublebond group into the terminal of the resulting living polymer by areaction with a various kind of reagent, and then conducting aprotection-removing reaction of the functional group which has beenformed by protecting the acidic group by a hydrolysis reaction, ahydrogenolysis reaction, an oxidative decomposition reaction, or aphotodecomposition reaction to generate the acidic group.

An example thereof is shown by the following reaction scheme (1):##STR40##

The living polymer can be easily synthesized according to synthesismethods as described, e.g., in P. Lutz, P. Masson et al, Polym. Bull.,12, 79 (1984), B. C. Anderson, G. D. Andrews et al, Macromolecules, 14,1601 (1981), K. Hatada, K. Ute et al, Polym. J., 17, 977 (1985), ibid.,18, 1037 (1986), Koichi Migite and Koichi Hatada, Kobunshi Kako (PolymerProcessing), 36, 366 (1987), Toshinobu Higashimura and Mitsuo Sawamoto,Kobunshi Ronbun Shu (Polymer Treatises), 46, 189 (1989), M. Kuroki andT. Aida, J. Am. Chem. Soc., 109, 4737 (1987), Teizo Aida and ShoheiInoue, Yuki Gosei Kagaku (Organic Synthesis Chemistry), 43, 300 (1985),and D. Y. Sogoh, W. R. Hertler et al, Macromolecules, 20, 1473 (1987).

In order to introduce a polymerizable double bond group into theterminal of the living polymer, a conventionally known synthesis methodfor macromonomer can be employed.

For details, reference can be made, for example, to P. Dreyfuss and R.P. Quirk, Encycl. Polym. Sci. Eng., 7, 551 (1987), P. F. Rempp and E.Franta, Adu., Polym. Sci., 58, 1 (1984), V. Percec, Appl. Polym. Sci.,285, 95 (1984), R. Asami and M. Takari, Makromol. Chem. Suppl., 12, 163(1985), P. Rempp et al., Makromol. Chem. Suppl., 8, 3 (1984), YushiKawakami, Kogaku Kogyo, 38, 56 (1987), Yuya Yamashita, Kobunshi, 31, 988(1982), Shiro Kobayashi, Kobunshi, 30, 625 (1981), ToshinobuHigashimura, Nippon Secchaku Kyokaishi, 18, 536 (1982), Koichi Itoh,Kobunshi Kako, 35, 262 (1986), Kishiro Higashi and Takashi Tsuda, KinoZairyo, 1987, No. 10, 5, and references cited in these literatures.

Also, the protection of the specific acidic group of the presentinvention and the release of the protective group (a reaction forremoving a protective group) can be easily conducted by utilizingconventionally known techniques. More specifically, they can beperformed by appropriately selecting methods as described, e.g., inYoshio Iwakura and Keisuke Kurita, Hannosei Kobunshi (Reactive Polymer),published by Kodansha (1977), T. W. Greene, Protective Groups in OrganicSynthesis, published by John Wiley & Sons (1981), and J. F. W. McOmie,Protective Groups in Organic Chemistry, Plenum Press, (1973), as well asmethods as described in the above references.

Furthermore, the AB block copolymer can be also synthesized by aphotoinifeter polymerization method using a dithiocarbamate compound asan initiator. For example, the block copolymer can be synthesizedaccording to synthesis methods as described, e.g., in Takayuki Otsu,Kobunshi (Polymer), 37, 248 (1988), Shunichi Himori and Ryuichi Ohtsu,Polym. Rep. Jap. 37, 3508 (1988), JP-A-64-111, and JP-A-64-26619.

The macromonomer (M) according to the present invention can be obtainedby applying the above described synthesis method for macromonomer to theAB block copolymer.

Specific examples of the macromonomer (M) which can be used in thepresent invention are set forth below, but the present invention shouldnot be construed as being limited thereto. In the following formulae,Q₃, Q₄ and Q₅ each represents --H, --CH₃ or --CH₂ COOCH₃ ; Q₆ represents--H or --CH₃ ; R₃₁ represents --C_(n) H_(2n+1) (wherein n represents aninteger of from 1 to 18), ##STR41## (wherein t represents an integer offrom 1 to 3), ##STR42## (wherein X represents --H, --Cl, --Br, --CH₃,--OCH₃ or --COCH₃) or ##STR43## (wherein p represents an integer of from0 to 3); R₃₂ represents --C_(q) H_(2q+1) (wherein q represents aninteger of from 1 to 8) or ##STR44## Y₁ represents --OH, --COOH, --SO₃H, ##STR45## Y₂ represents --COOH, --SO₃ H, ##STR46## r represents andinteger of from 2 to 12; s represents an integer of from 2 to 6; and--b-- is as defined above. ##STR47##

The monomer copolymerizable with the macromonomer (M) described above ispreferably selected from those represented by the general formula (III)described above. In the general formula (III), b₃, b₄, X₂ and R₂₂ eachhas the same meaning as defined for b₁, b₂, X₁ and R₂₁ in the generalformula (II) as described above. Specifically, b₃ and b₄ each representsa hydrogen atom, a halogen atom, a cyano group, a hydrocarbon group,--COOR₂₄ ' or --COOR₂₄ ' bonded via a hydrocarbon group (wherein R₂₄ 'represents a hydrocarbon group); X₂ represents --COO--, --OCO--,--CH₂)_(l11) OCO--, --COO--, --OCO--, --CH₂)_(l11) OCO`, --CH₂)_(l12)COO-- (wherein L₁₁ and l₁₂ each represents an integer of from 1 to 3),--O--, --SO₂ --, --CO--, ##STR48## (wherein R₂₃ ' represent a hydrogenatom or a hydrocarbon group), --CONHCOO--, --CONHCONH--, or ##STR49##and R₂₂ represents a hydrocarbon group, provided that when X₂ represents##STR50## R₂₂ represents a hydrogen atom or a hydrocarbon group. Morepreferably, b₃ represents a hydrogen atom, b₄ represents a methyl group,and X₂ represents --COO--.

In the resin (B) used in the present invention, a ratio of the A blockto the B block in the macromonomer (M) preferably ranges from 1 to 30/99to 70 by weight. The content of the acidic group-containing component inthe resin (B) is preferably from 0.1 to 20% by weight, more preferablyfrom 0.5 to 10% by weight. A ratio of the copolymer component having themacromonomer (M) as a repeating unit to the copolymer component havingthe monomer represented by the general formula (III) as a repeating unitranges preferably from 1 to 60/99 to 40 by weight, more preferably 5 to50/95 to 50 by weight.

The binder resin (B) according to the present invention can be producedby copolymerization of the corresponding mono-functional polymerizablecompounds in the desired ratio. The copolymerization can be performedusing a known polymerization method, for example, solutionpolymerization, suspension polymerization, precipitation polymerization,and emulsion polymerization. More specifically, according to thesolution polymerization monomers are added to a solvent such as benzeneor toluene in the desired ratio and polymerized with an azobis compound,a peroxide compound or a radical polymerization initiator to prepare acopolymer solution. The solution is dried or added to a poor solventwhereby the desired copolymer can be obtained. In case of suspensionpolymerization, monomers are suspended in the presence of a dispersingagent such as polyvinyl alcohol or polyvinyl pyrrolidone andcopolymerized with a radical polymerization initiator to obtain thedesired copolymer.

As the binder resin of the photoconductive layer according to thepresent invention, a resin which is conventionally used as a binderresin for electrophotographic light-sensitive materials can be employedin combination with the above described binder resin according to thepresent invention. Examples of such resins are described, for example,in Harumi Miyamoto and Hidehiko Takei, Imaging, Nos. 8 and 9 to 12, 1978and Ryuji Kurita and Jiro Ishiwata, Kobunshi (Polymer), 17, 278-284(1968).

Specific examples thereof include an olefin polymer, an olefincopolymer, a vinyl chloride copolymer, a vinylidene chloride copolymer,a vinyl alkanoate polymer, a vinyl alkanoate copolymer, an allylalkanoate polymer, an allyl alkanoate copolymer, a styrene and styrenederivative polymer, a styrene and styrene derivative copolymer, abutadiene-styrene copolymer, an isoprene-styrene copolymer, abutadiene-unsaturated carboxylic acid ester copolymer, an acrylonitrilecopolymer, a methacrylonitrile copolymer, an alkyl vinyl ethercopolymer, acrylic acid ester polymer and copolymer, a methacrylic acidester polymer and copolymer, a styrene-acrylic acid ester copolymer, astyrene-methacrylic acid ester copolymer, itaconic acid diester polymerand copolymer, a maleic anhydride copolymer, an acrylamide copolymer, amethacrylamide copolymer, a hydroxy group-modified silicone resin, apolycarbonate resin, a ketone resin, an amide resin, a hydroxy group-and carboxy group-modified polyester resin, a butyral resin, a polyvinylacetal resin, a cyclized rubber-methacrylic acid ester copolymer, acyclized rubber-acrylic acid ester copolymer, a copolymer having aheterocyclic group containing no nitrogen atom (examples of theheterocyclic ring are a furan ring, a tetrahydrofuran ring, a thiophenering, a dioxane ring, a dioxolan ring, a lactone ring, a benzofuranring, a benzothiophene ring, and a 1,3-dioxetane ring), and an epoxyresin.

However, it is preferred that such resins are employed in a range of notmore than 30% by weight based on the whole binder resin.

The ratio of the resin (A) to the resin (B) is not particularlyrestricted, but ranges preferably from 5 to 50/95 to 50 by weight, morepreferably from 10 to 0/90 to 60 by weight.

The inorganic photoconductive substance which can be used in the presentinvention includes zinc oxide, titanium oxide, zinc sulfide, cadmiumsulfide, cadmium carbonate, zinc selenide, cadmium selenide, telluriumselenide, and lead sulfide, preferably zinc oxide.

The resin binder is used in a total amount of from 10 to 100 parts byweight, preferably from 15 to 50 parts by weight, per 100 parts byweight of the inorganic photoconductive substance.

If desired, various dyes can be used as spectral sensitizer in thepresent invention. Examples of the spectral sensitizers are carboniumdyes, diphenylmethane dyes, triphenylmethane dyes, xanthene dyes,phthalein dyes, polymethine dyes (e.g., oxonol dyes, merocyanine dyes,cyanine dyes, rhodacyanine dyes, and styryl dyes), and phthalocyaninedyes (including metallized dyes). Reference can be made to, for example,in Harumi Miyamoto and Hidehiko Takei, Imaging, 1973, No. 8, 12, C. J.Young et al., RCA Review, 15, 469 (1954), Ko-hei Kiyota et al.,Denkitsushin Gakkai Ronbunshi, J 63-C, No. 2, 97 (1980), Yuji Harasakiet al., Kogyo Kagaku Zasshi, 66, 78 and 188 (1963), and Tadaaki Tani,Nihon Shashin Gakkaishi, 35, 208 (1972).

Specific examples of the carbonium dyes, triphenylmethane dyes, xanthenedyes, and phthalein dyes are described, for example, in JP-B-51-452,JP-A-50-90334, JP-A-50-114227, JP-A-53-39130, JP-A-53-82353, U.S. Pat.Nos. 3,052,540 and 4,054,450, and JP-A-57-16456.

The polymethine dyes, such as oxonol dyes, merocyanine dyes, cyaninedyes, and rhodacyanine dyes, include those described, for example, in F.M. Hammer, The Cyanine Dyes and Related Compounds. Specific examplesinclude those described, for example, in U.S. Pat. Nos. 3,047,384,3,110,591, 3,121,008, 3,125,447, 3,128,179, 3,132,942, and 3,622,317,British Patents 1,226,892, 1,309,274 and 1,405,898, JP-B-48-7814 andJP-B-55-18892.

In addition, polymethine dyes capable of spectrally sensitizing in thelonger wavelength region of 700 nm or more, i.e., from the near infraredregion to the infrared region, include those described, for example, inJP-A-47-840, JP-A-47-44180, JP-B-51-41061, JP-A-49-5034, JP-A-49-45122,JP-A-57-46245, JP-A-56-35141, JP-A-57-157254, JP-A-61-26044,JP-A-61-27551, U.S. Pat. Nos. 3,619,154 and 4,175,956, and Researchdisclosure, 216, 117 to 118 (1982).

The light-sensitive material of the present invention is particularlyexcellent in that the performance properties are not liable to variationeven when combined with various kinds of sensitizing dyes.

If desired, the photoconductive layer may further contain variousadditives commonly employed in conventional electrophotographiclight-sensitive layer, such as chemical sensitizers. Examples of suchadditives include electron-accepting compounds (e.g., halogen,benzoquinone, chloranil, acid anhydrides, and organic carboxylic acids)as described in the above-mentioned Imaging, 1973, No. 8, 12; andpolyarylalkane compounds, hindered phenol compounds, andp-phenylenediamine compounds as described in Hiroshi Kokado et al.,Saikin-no Kododen Zairyo to Kankotai no Kaihatsu Jitsuyoka, Chaps. 4 to6, Nippon Kagaku Joho K.K. (1986).

The amount of these additives is not particularly restricted and usuallyranges from 0.0001 to 2.0 parts by weight per 100 parts by weight of thephotoconductive substance.

The photoconductive layer suitably has a thickness of from 1 to 100 μm,preferably from 10 to 50 μm.

In cases where the photoconductive layer functions as a chargegenerating layer in a laminated light-sensitive material composed of acharge generating layer and a charge transporting layer, the thicknessof the charge generating layer suitably ranges from 0.01 to 1 μm,particularly from 0.05 to 0.5 μm.

If desired, an insulating layer can be provided on the light-sensitivelayer of the present invention. When the insulating layer is made toserve for the main purposes for protection and improvement of durabilityand dark decay characteristics of the light-sensitive material, itsthickness is relatively small. When the insulating layer is formed toprovide the light-sensitive material suitable for application to specialelectrophotographic processes, its thickness is relatively large,usually ranging from 5 to 70 μm, particularly from 10 to 50 μm.

Charge transporting material in the above-described laminatedlight-sensitive material include polyvinylcarbazole, oxazole dyes,pyrazoline dyes, and triphenylmethane dyes. The thickness of the chargetransporting layer ranges from 5 to 40 μm, preferably from 10 to 30 μm.

Resins to be used in the insulating layer or charge transporting layertypically include thermoplastic and thermosetting resins, e.g.,polystyrene resins, polyester resins, cellulose resins, polyetherresins, vinyl chloride resins, vinyl acetate resins, vinylchloride-vinyl acetate copolymer resins, polyacrylate resins, polyolefinresins, urethane resins, epoxy resins, melamine resins, and siliconeresins.

The photoconductive layer according to the present invention can beprovided on any known support. In general, a support for anelectrophotographic light-sensitive layer is preferably electricallyconductive. Any of conventionally employed conductive supports may beutilized in the present invention. Examples of usable conductivesupports include a substrate (e.g., a metal sheet, paper, and a plasticsheet) having been rendered electrically conductive by, for example,impregnating with a low resistant substance; the above-describedsubstrate with the back side thereof (opposite to the light-sensitivelayer side) being rendered conductive and having further coated thereonat least one layer for the purpose of prevention of curling; theabove-described substrate having provided thereon a water-resistantadhesive layer; the above-described substrate having provided thereon atleast one precoat layer; and paper laminated with a conductive plasticfilm on which aluminum is vapor deposited.

Specific examples of conductive supports and materials for impartingconductivity are described, for example, in Yukio Sakamoto,Denshishashin, 14, No. 1, pp. 2 to 11 (1975), Hiroyuki Moriga, NyumonTokushushi no Kagaku, Kobunshi Kankokai (1975), and M. F. Hoover, J,Macromol. Sci. Chem., A-4(6), pp. 1327 to 1417 (1970).

In accordance with the present invention, an electrophotographiclight-sensitive material which exhibits excellent electrostaticcharacteristics and mechanical strength even under severe conditions.The electrophotographic light-sensitive material according to thepresent invention is also advantageously employed in the scanningexposure system using a semiconductor laser beam.

The present invention will now be illustrated in greater detail withreference to the following examples, but it should be understood thatthe present invention is not to be construed as being limited thereto.

SYNTHESIS EXAMPLE A-1 Synthesis of Resin (A-1)

A mixed solution of 96 g of benzyl methacrylate, 4 g of thiosalicylicacid, and 200 g of toluene was heated to 75° C. in a nitrogen stream,and 1.0 g of 2,2'-azobisisobutyronitrile (hereinafter abbreviated asAIBN) was added thereto to effect reaction for 4 hours. To the reactionmixture was further added 0.4 g of AIBN, followed by reacting for 2hours, and thereafter 0.2 g of AIBN was added thereto, followed byreacting for 3 hours with stirring. The resulting copolymer (A-1) had aweight average molecular weight (hereinafter simply referred to as Mw)of 6.8×10³. ##STR51##

SYNTHESIS EXAMPLES A-2 TO A-13 Synthesis of Resins (A-2) to (A-13)

Resins (A) shown in Table 1 below were synthesized in the same manner asdescribed in Synthesis Example A-1, except for using the monomersdescribed in Table 1 below in place of 96 g of benzyl methacrylate,respectively. These resins had an Mw of from 6.0×10³ to 8.0×10³.

                                      TABLE 1                                     __________________________________________________________________________     ##STR52##                                                                    Synthesis                                                                     Example No.                                                                          Resin (A)                                                                           R              Y         x/y (weight ratio)                      __________________________________________________________________________    A-2    (A-2) C.sub.2 H.sub.5                                                                              --        96/0                                    A-3    (A-3) C.sub.6 H.sub.5                                                                              --        96/0                                    A-4    (A-4)                                                                                ##STR53##     --        96/0                                    A-5    (A-5)                                                                                ##STR54##     --        96/0                                    A-6    (A-6) CH.sub.3                                                                                      ##STR55##                                                                               86/10                                  A-7    (A-7) C.sub.2 H.sub.5                                                                               ##STR56##                                                                               86/10                                  A-8    (A-8)                                                                                ##STR57##                                                                                    ##STR58##                                                                               66/30                                  A-9    (A-9)                                                                                ##STR59##     --        96/0                                     A-10   (A-10)                                                                              ##STR60##     --        96/0                                     A-11   (A-11)                                                                              ##STR61##     --        96/0                                     A-12   (A-12)                                                                              ##STR62##                                                                                    ##STR63##                                                                               76/20                                   A-13   (A-13)                                                                             CH.sub.2 CH.sub.2 OC.sub.6 H.sub.5                                                           --        96/0                                    __________________________________________________________________________

SYNTHESIS EXAMPLES A-14 TO A-24 Synthesis of Resins (A-14) to (A-24)

Resins (A) shown in Table 2 below were synthesized under the samereaction conditions as described in Synthesis Example A-1, except forusing the methacrylates and mercapto compounds described in Table 2below in place of 96 g of benzyl methacrylate and 4 g of thiosalicylicacid and replacing 200 g of toluene with 150 g of toluene and 50 g ofisopropanol, respectively.

                                      TABLE 2                                     __________________________________________________________________________     ##STR64##                                                                    Synthesis                                             Weight Average          Example No.                                                                          Resin (A)                                                                            Mercapto Compound (W)   R               Molecular               __________________________________________________________________________                                                          Weight                  A-14   (A-14) HOOCCH.sub.2 CH.sub.2 CH.sub.2                                                                    4 g C.sub.2 H.sub.5                                                                           96 g                                                                              7.3 ×                                                                   10.sup.3                A-15   (A-15) HOOCCH.sub.2        5 g C.sub.3 H.sub.7                                                                           95 g                                                                              5.8 ×                                                                   10.sup.3                A-16   (A-16)                                                                                ##STR65##          5 g CH.sub.2 C.sub.6 H.sub.5                                                                  95 g                                                                              7.5 ×                                                                   10.sup.3                A-17   (A-17) HOOCCH.sub.2 CH.sub.2                                                                             5.5 g                                                                             C.sub.6 H.sub.5                                                                           94.5 g                                                                            6.5 ×                                                                   10.sup.3                A-18   (A-18) HOOCCH.sub.2        4 g                                                                                ##STR66##  96 g                                                                              5.3 ×                                                                   10.sup.3                A-19   (A-19)                                                                                ##STR67##          3 g                                                                                ##STR68##  97 g                                                                              6.0 ×                                                                   10.sup.3                A-20   (A-20) HO.sub.3 SCH.sub.2 CH.sub.2                                                                       3 g                                                                                ##STR69##  97 g                                                                              8.8 ×                                                                   10.sup.3                A-21   (A-21)                                                                                ##STR70##          4 g                                                                                ##STR71##  96 g                                                                              7.5 ×                                                                   10.sup.3                A-22   (A-22)                                                                                ##STR72##          7 g                                                                                ##STR73##  93 g                                                                              5.5 ×                                                                   10.sup.3                A-23   (A-23)                                                                                ##STR74##          6 g                                                                                ##STR75##  94 g                                                                              4.5 ×                                                                   10.sup.3                A-24   (A-24)                                                                                ##STR76##          4 g                                                                                ##STR77##  96 g                                                                              5.6 ×             __________________________________________________________________________                                                          10.sup.3            

SYNTHESIS EXAMPLE A-25 Synthesis of Resin (A-25)

A mixed solution of 100 g of 1-naphthyl methacrylate, 150 g of tolueneand 50 g of isopropanol was heated to 80° C. in a nitrogen stream, and5.0 g of 4,4'-azobis(4-cyanovaleric acid) (hereinafter abbreviated as"ACV") was added thereto, followed by reacting with stirring for 5hours. Then, 1 g of ACV was added thereto, followed by reacting withstirring for 2 hours, and thereafter 1 g of ACV was added thereto,followed by reacting with stirring for 3 hours. The resulting copolymer(A-25) had a weight average molecular weight of 7.5×10³. ##STR78##

SYNTHESIS EXAMPLE A-26 Synthesis of Resin (A-26)

A mixed solution of 50 g of methyl methacrylate and 150 g of methylenechloride was cooled to -20° C. in a nitrogen stream, and 5 g of a 10%hexane solution of 1,1-diphenylhexyl lithium prepared just before wasadded thereto, followed by stirring for 5 hours. Carbon dioxide waspassed through the mixture at a flowing rate of 10 ml/cc for 10 minuteswith stirring, the cooling was stopped and the reaction mixture wasallowed to stand to room temperature with stirring. Then, the reactionmixture was added to a solution of 50 ml of 1N hydrochloric acid in 1liter of methanol to precipitate, and the white powder was collected byfiltration. The powder was washed with water until the washings becameneutral, and dried under reduced pressure to obtain 18 g of thecopolymer having a weight average molecular weight of 6.5×10³. ##STR79##

SYNTHESIS EXAMPLE A-27 Synthesis of Resin (A-27)

A mixed solution of 95 g of n-butyl methacrylate, 4 g of thioglycolicacid, and 200 g of toluene was heated to 75° C. in a nitrogen stream,and 1.0 g of ACV was added thereto to effect reaction for 6 hours. Then,0.4 g of AIBN was added thereto, followed by reacting for 3 hours. Theresulting copolymer had a weight average molecular weight of 7.8×10³.##STR80##

SYNTHESIS EXAMPLE M-1 Synthesis of Macromonomer (M-1)

A mixed solution of 10 g of triphenylmethyl methacrylate, and 200 g oftoluene was sufficiently degassed in a nitrogen stream and cooled to-20° C. Then, 0.02 g of 1,1-diphenylbutyl lithium was added to themixture, and the reaction was conducted for 10 hours. Separately, amixed solution of 90 g of ethyl methacrylate and 100 g of toluene wassufficiently degassed in a nitrogen stream and the resulting mixedsolution was added to the above described mixture, and then reaction wasfurther conducted for 10 hours. The reaction mixture was adjusted to 0°C., and carbon dioxide gas was passed through the mixture in a flow rateof 60 ml/min for 30 minutes, then the polymerization reaction wasterminated.

The temperature of the reaction solution obtained was raised to 25° C.under stirring, 6 g of 2-hydroxyethyl methacrylate was added thereto,then a mixed solution of 10 g of dicyclohexylcarbodiimide, 0.2 g of4-N,N-dimethylaminopyridine and 30 g of methylene chloride was addeddropwise thereto over a period of 30 minutes, and the mixture wasstirred for 3 hours. After removing the insoluble substances from thereaction mixture by filtration, 10 ml of an ethanol solution of 30 % byweight hydrogen chloride was added to the filtrate and the mixture wasstirred for one hour. Then, the solvent of the reaction mixture wasdistilled off under reduced pressure until the whole volume was reducedto a half, and the mixture was reprecipitated from one liter ofpetroleum ether.

The precipitates thus formed were collected and dried under reducedpressure to obtain 56 g of Macromonomer (M-1) shown below having an Mwof 6.5×10³. ##STR81##

SYNTHESIS EXAMPLE M-2 Synthesis of Macromonomer (M-2)

A mixed solution of 5 g of benzyl methacrylate, 0.01 g of (tetraphenylporphynate) aluminum methyl, and 60 g of methylene chloride was raisedto a temperature of 30° C. in a nitrogen stream. The mixture wasirradiated with light from a xenon lamp of 300 W at a distance of 25 cmthrough a glass filter, and the reaction was conducted for 12 hours. Tothe mixture was further added 45 g of butyl methacrylate, aftersimilarly light-irradiating for 8 hours, 5 g of 4-bromomethylstyrene wasadded to the reaction mixture followed by stirring for 30 minutes, thenthe reaction was terminated. Then, Pd-C was added to the reactionmixture, and a catalytic reduction reaction was conducted for one hourat 25° C.

After removing insoluble substances from the reaction mixture byfiltration, the reaction mixture was reprecipitated from 500 ml ofpetroleum ether and the precipitates thus formed were collected anddried to obtain 33 g of Macromonomer (M-2) shown below having an Mw of7×10³. ##STR82##

SYNTHESIS EXAMPLE M-3 Synthesis of Macromonomer (M-3)

A mixed solution of 20 g of 4-vinylphenyloxytrimethylsilane and 100 g oftoluene was sufficiently degassed in a nitrogen stream and cooled to 0°C. Then, 0.1 g of 1,1-diphenyl-3-methylpentyl lithium was added to themixture followed by stirring for 6 hours. Separately, a mixed solutionof 80 g of 2-chloro-6-methylphenyl methacrylate and 100 g of toluene wassufficiently degassed in a nitrogen stream and the resulting mixedsolution was added to the above described mixture, and then reaction wasfurther conducted for 8 hours. After introducing ethylene oxide in aflow rate of 30 ml/min into the reaction mixture for 30 minutes withvigorously stirring, the mixture was cooled to a temperature of 15° C.,and 8 g of methacrylic chloride was added dropwise thereto over a periodof 30 minutes, followed by stirring for 3 hours.

Then, to the reaction mixture was added 10 ml of an ethanol solution of30% by weight hydrogen chloride and, after stirring the mixture for onehour at 25° C., the mixture was reprecipitated from one liter ofpetroleum ether. The precipitates thus formed were collected, washedtwice with 300 ml of diethyl ether and dried to obtain 55 g ofMacromonomer (M-3) shown below having an Mw of 7.8×10³. ##STR83##

SYNTHESIS EXAMPLE M-4 Synthesis of Macromonomer (M-4)

A mixed solution of 15 g of triphenylmethyl acrylate and 100 g oftoluene was sufficiently degassed in a nitrogen stream and cooled to-20° C. Then, 0.1 g of sec-butyl lithium was added to the mixture, andthe reaction was conducted for 10 hours. Separately, a mixed solution of85 g of styrene and 100 g of toluene was sufficiently degassed in anitrogen stream and the resulting mixed solution was added to the abovedescribed mixture, and then reaction was further conducted for 12 hours.The reaction mixture was adjusted to 0° C., 8 g of benzyl bromide wasadded thereto, and the reaction was conducted for one hour, followed byreacting at 25° C. for 2 hours.

Then, to the reaction mixture was added 10 ml of an ethanol solution of30% by weight hydrogen chloride, followed by stirring for 2 hours. Afterremoving the insoluble substances from the reaction mixture byfiltration, the mixture was reprecipitated from one liter of n-hexane.The precipitates thus formed were collected and dried under reducedpressure to obtain 58 g of Macromonomer (M-4) shown below having an Mwof 4.5 ×10³. ##STR84##

SYNTHESIS EXAMPLE M-5 Synthesis of Macromonomer (M-5)

A mixed solution of 80 g of phenyl methacrylate and 4.8 g of benzylN-hydroxyethyl-N-ethyldithiocarbamate was placed in a vessel in anitrogen stream followed by closing the vessel and heated to 60° C. Themixture was irradiated with light from a high-pressure mercury lamp for400 W at a distance of 10 cm through a glass filter for 10 hours toconduct a photopolymerization.

Then, 20 g of acrylic acid and 180 g of methyl ethyl ketone were addedto the mixture and, after replacing the gas in the vessel with nitrogen,the mixture was light-irradiated again for 10 hours.

To the reaction mixture was added dropwise 6 g of 2-isocyanatoethylmethacrylate at 30° C. over a period of one hour and the mixture wasstirred for 2 hours. The reaction mixture was reprecipitated from 1.5liters of hexane and the precipitates thus formed were collected anddried to obtain 68 g of Macromonomer (M-5) shown below having an Mw of6.0×10³. ##STR85##

SYNTHESIS EXAMPLE B-1 Synthesis of Resin (B-1)

A mixed solution of 80 g of ethyl methacrylate, 20 g of Macromonomer(M-1) and 150 g of toluene was heated at 65° C. in a nitrogen stream,and 0.8 g of AIBN was added thereto to effect reaction for 4 hours.Then, 0.4 g of AIBN was further added thereto, followed by reacting for3 hours and thereafter 0.4 g of AIBN was further added, followed byreacting for 3 hours. The resulting copolymer shown below had an Mw of8×10⁴. ##STR86##

SYNTHESIS EXAMPLE B-2 Synthesis of Resin (B-2)

A mixed solution of 70 g of benzyl methacrylate, 30 g of Macromonomer(M-1), and 100 g of toluene was heated at 85° C. in a nitrogen stream,and 1.0 g of 1,1-azobis(cyclohexane-1-carbonitrile) (hereinafter simplyreferred to as ABCC) was added thereto to effect reaction for 5 hours.Then, 0.5 g of ABCC was further added, followed by reacting for 5 hoursand thereafter 0.4 g of ABCC was further added, followed by raising thetemperature to 90° C. and reacting for 3 hours. The resulting copolymershown below had an Mw of 1×10⁵. ##STR87##

SYNTHESIS EXAMPLES B-3 TO B-18 Synthesis of Resins (B-3) to (B-18)

Resins (B) shown in Table 3 below were synthesized under the samepolymerization conditions as described in Synthesis Example B-1 exceptfor changing ethyl methacrylate to the monomer shown in Table 3 below.Each of these resins had an Mw of from 7×10⁴ to 9×10⁴.

                                      TABLE 3                                     __________________________________________________________________________     ##STR88##                                                                    Synthesis                                                                     Example No.                                                                          Resin (B)                                                                          R              Y            x/y                                   __________________________________________________________________________    3      B-3  C.sub.4 H.sub.9                                                                              --           80/0                                  4      B-4  CH.sub.3       --           80/0                                  5      B-5  C.sub.6 H.sub.5                                                                              --           80/0                                  6      B-6  C.sub.2 H.sub.5                                                                               ##STR89##   65/15                                 7      B-7  CH.sub.2 C.sub.6 H.sub.5                                                                      ##STR90##   70/10                                 8      B-8  C.sub.3 H.sub.7                                                                              --           80/0                                  9      B-9  C.sub.2 H.sub.5                                                                               ##STR91##   70/10                                 10     B-10 CH.sub.3                                                                                      ##STR92##   70/10                                 11     B-11                                                                                ##STR93##                                                                                    ##STR94##   65/15                                 12     B-12                                                                                ##STR95##                                                                                    ##STR96##   65/15                                 13     B-13 CH.sub.3                                                                                      ##STR97##   70/10                                 14     B-14 C.sub.6 H.sub.5                                                                              --           80/0                                  15     B-15 CH.sub.3                                                                                      ##STR98##   40/40                                 16     B-16 CH.sub. 2 C.sub.6 H.sub.5                                                                     ##STR99##   65/15                                 17     B-17 C.sub.6 H.sub.5                                                                               ##STR100##  72/8                                  18     B-18                                                                                ##STR101##    --           80/0                                  __________________________________________________________________________

SYNTHESIS EXAMPLES B-19 TO B-35 Synthesis of Resins (B-19) to (B-35)

Resins (B) shown in Table 4 below were synthesized under the samepolymerization conditions as described in Synthesis Example B-2 exceptfor using the macromonomer (M) shown in Table 4 below in place ofMacromonomer (M-1) respectively. Each of these resins had an Mw of from7×10⁴ to 1.2×10⁵.

                                      TABLE 4                                     __________________________________________________________________________     ##STR102##                                                                   Synthesis                                                                     Example                                                                            Resin                                                                    No.  (B) X              a.sub.1 /a.sub.2                                                                      R         Z                y/z                __________________________________________________________________________    19   B-19                                                                              COO(CH.sub.2).sub.2 OOC                                                                      H/CH.sub.3                                                                            COOCH.sub.3                                                                              ##STR103##      90/10              20   B-20                                                                               ##STR104##    CH.sub.3 /CH.sub.3                                                                    COOCH.sub.2 C.sub.6 H.sub.5                                                              ##STR105##      90/10              21   B-21                                                                               ##STR106##    H/CH.sub.3                                                                            COOC.sub.6 H.sub.5                                                                       ##STR107##      80/20              22   B-22                                                                              COO(CH.sub.2).sub.2 OCO(CH.sub.2).sub.2 COO(CH.sub.2).sub.2                                  CH.sub.3 /CH.sub.3                                                                    COOC.sub.2 H.sub.5                                                                       ##STR108##      92/8               23   B-23                                                                              COOCH.sub.2 CH.sub.2                                                                         CH.sub.3 /H                                                                           C.sub.6 H.sub.5                                                                          ##STR109##      80/20              24   B-24                                                                               ##STR110##    CH.sub.3 /CH.sub.3                                                                    COOC.sub.2 H.sub.5                                                                       ##STR111##      94/6               25   B-25                                                                               ##STR112##    H/CH.sub.3                                                                            COOC.sub.3 H.sub.7                                                                       ##STR113##      85/15              26   B-26                                                                               ##STR114##    CH.sub.3 /CH.sub.3                                                                    COOC.sub.2 H.sub.5                                                                       ##STR115##      88/12              27   B-27                                                                              "              CH.sub.3 /H                                                                           COOC.sub.6 H.sub.5                                                                       ##STR116##      90/10              28   B-28                                                                              COO(CH.sub.2).sub.2 NHCOO (CH.sub.2).sub.2                                                   CH.sub.3 /CH.sub.3                                                                    "                                                                                        ##STR117##      92/8               29   B-29                                                                              COOCH.sub.2 CH.sub.2                                                                         CH.sub.3 /H                                                                           C.sub.6 H.sub.5                                                                          ##STR118##      92/8               30   B-30                                                                               ##STR119##    CH.sub.3 /CH.sub.3                                                                    COOCH.sub.2 C.sub.6 H.sub.5                                                              ##STR120##      90/10              31   B-31                                                                               ##STR121##    H/CH.sub.3                                                                            COOC.sub.4 H.sub.9                                                                       ##STR122##      90/10              32   B-32                                                                              COO            CH.sub.3 /CH.sub.3                                                                    COOCH.sub.3                                                                              ##STR123##      91/9               33   B-33                                                                               ##STR124##    CH.sub.3 /CH.sub.3                                                                     ##STR125##                                                                              ##STR126##      85/15              34   B-34                                                                               ##STR127##    H/H     C.sub.6 H.sub.5                                                                          ##STR128##      90/10              35   B-35                                                                               ##STR129##    H/CH.sub.3                                                                            COOCH.sub.2 C.sub.6 H.sub.5                                                              ##STR130##      94/6               __________________________________________________________________________

EXAMPLE 1

A mixture of 6 g (solid basis, hereinafter the same) of Resin (A-2), 34g (solid basis, hereinafter the same) of Resin (B-1), 200 g of zincoxide, 0.018 g of Cyanine Dye (I) shown below, 0.10 g of salicylic acid,and 300 g of toluene was dispersed in a ball mill for 3 hours to preparea coating composition for a light-sensitive layer. The coatingcomposition was coated on paper, which had been subjected toelectrically conductive treatment, by a wire bar to a dry coverage of 18g/m², followed by drying at 110° C. for 30 seconds. The coated materialwas allowed to stand in a dark place at 20° C. and 65% RH (relativehumidity) for 24 hours to prepare an electrophotographic light-sensitivematerial. ##STR131##

EXAMPLE 2

An electrophotographic light-sensitive material was prepared in the samemanner as described in Example 1, except for using 6 g of Resin (A-4) inplace of 6 g of Resin (A-2).

COMPARATIVE EXAMPLE A

An electrophotographic light-sensitive material was prepared in the samemanner as described in Example 1, except for using 34 g of poly(ethylmethacrylate) having an Mw of 2.4×10⁵ (Resin (R-1)) in place of 34 g ofResin (B-1).

COMPARATIVE EXAMPLE B

An electrophotographic light-sensitive material was prepared in the samemanner as described in Example 1, except for using 34 g of Resin (R-2)shown below in place of 34 g of Resin (B-1). ##STR132##

Each of the light-sensitive materials thus obtained in Examples 1 and 2and Comparative Examples A and B was evaluated for film properties interms of surface smoothness and mechanical strength; electrostaticcharacteristics; image forming performance; oil-desensitivity when usedas an offset master plate precursor (expressed in terms of contact angleof the layer with water after the oil-desensitization treatment); andprinting suitability (expressed in terms of background stains andprinting durability). The results obtained are shown in Table 5 below.

                                      TABLE 5                                     __________________________________________________________________________                                Comparative                                                                          Comparative                                                Example 1                                                                           Example 2                                                                           Example A                                                                            Example B                                  __________________________________________________________________________    Surface Smoothness*.sup.1) (sec/cc)                                                           140   145   150    140                                        Mechanical Strength*.sup.2) (%)                                                               97    96    88     93                                         Electrostatic Characteristics*.sup.3) :                                       V.sub.10 (-V):                                                                         Condition I                                                                          480   610   460    475                                                 Condition II                                                                         465   605   450    465                                        DRR (%): Condition I                                                                          80    88    76     78                                                  Condition II                                                                         78    85    70     75                                         E.sub.1/10 (erg/cm.sup.2):                                                             Condition I                                                                          28    17    36     35                                                  Condition II                                                                         25    18    40     40                                         E.sub.1/100 (erg/cm.sup.2):                                                            Condition I                                                                          36    26    48     46                                                  Condition II                                                                         39    29    60     58                                         Image-Forming Performance*.sup.4) :                                                    Condition I                                                                          Good  Very  No Good                                                                              No Good                                                          Good  (slight edge                                                                         (slight edge                                                           mark of                                                                              mark of                                                                cutting)                                                                             cutting)                                            Condition II                                                                         Good  Very  Poor   Poor                                                             Good  (slight back-                                                                        (slight back-                                                    Good  ground fog,                                                                          ground fog,                                                            edge mark                                                                            edge mark                                                              of cutting)                                                                          of cutting)                                Contact Angle*.sup.5)                                                                         10 or less                                                                          10 or less                                                                          10 or less                                                                           10 or less                                 With Water (°)                                                         Printing Durability*.sup.6) :                                                                 10,000                                                                              10,000                                                                              Background                                                                           Background                                                             stains due                                                                           stains due to                                                          to edge mark                                                                         edge mark                                                              of cutting                                                                           of cutting                                                             from the start                                                                       from the start                                                         of printing                                                                          of printing                                __________________________________________________________________________

The evaluation described in Table 5 above were conducted as follows.

*1) Smoothness of Photoconductive Layer:

The smoothness (sec/cc) of light-sensitive material was measured using aBeck's smoothness test machine (manufactured by Kumagaya Riko K.K.)under an air volume condition of 1 cc.

*2) Mechanical Strength of Photoconductive Layer:

The surface of light-sensitive material was repeatedly rubbed 1,000times with emery paper (#1000) under a load of 60 g/cm² using a Heidon14 Model surface testing machine (manufactured by Shinto Kagaku K.K.).After removing abrasion dusts from the layer, the film retention (%) wasdetermined from the weight loss of the photoconductive layer, which wasreferred to as the mechanical strength.

*3) Electrostatic Characteristics:

The light-sensitive material was charged by applying thereto coronadischarge of -6 kV for 20 seconds using a paper analyzer (Paper AnalyzerType SP-428, manufactured by Kawaguchi Denki K.K.) in a dark place underconditions of 20° C. and 65% RH. Ten seconds after the corona discharge,the surface potential V₁₀ was measured. Then, the sample was allowed tostand for 180 seconds in a dark place and the potential V₁₉₀ wasmeasured. The dark decay retention rate (DRR (%)), i.e., the percentretention of potential after decaying for 180 seconds in a dark place,was calculated from the following equation: DRR (%)=(V₁₉₀ /V₁₀)×100 (%).

Also, the surface of the photoconductive layer was charged to -500 V bycorona discharge, then irradiated by monochromatic light of a wavelengthof 785 nm, the time required for decaying the surface potential (V₁₀) to1/10 thereof was measured, and the exposure amount E_(1/10) (erg/cm²)was calculated therefrom.

Further, the surface of the photoconductive layer was charged to -500 Vby corona discharge in the same manner as described for the measurementof E_(1/10), then irradiated by monochromatic light of a wavelength of785 nm, the time required for decaying the surface potential (V₁₀) to1/100 thereof was measured, and the exposure amount E_(1/100) (erg/cm²)was calculated therefrom.

The measurement were conducted under conditions of 20° C. and 65% RH(hereinafter referred to as Condition 1) or 30° C. and 80% RH(hereinafter referred to as Condition II).

*4) Image Forming Performance:

The light-sensitive material was allowed to stand for one day underCondition I or II. Then, under each of Conditions I and II the samplewas charged to -5 kV, irradiated by scanning with agallium-aluminum-arsenic semiconductor laser (oscillation wavelength:780 nm) of 2.8 mW output as a light source in an exposure amount on thesurface of 50 erg/cm², at a pitch of 25 μm and a scanning speed of 330m/sec., and then developed using ELP-T (made by Fuji Photo Film Co.,Ltd.) as a liquid developer followed by fixing. The duplicated imagethus obtained was visually evaluated for fog and image quality. Theoriginal used for the duplication was composed of letters by a wordprocessor and a cutting of letters on straw paper pasted upon thereon.

*5) Contact Angle with Water:

The light-sensitive material was passed once through an etchingprocessor using an oil-desensitizing solution (ELP-EX, made by FujiPhoto Film Co., Ltd.) diluted to a 2-fold volume with distilled water todesensitize the surface of the photoconductive layer. Then, a drop of 2μl of distilled water was placed on the surface, and the contact angleformed between the surface and the water drop thereon was measured usinga goniometer.

*6) Printing Durability:

The light-sensitive material was subjected to the plate making under thesame conditions as described in *4) above to form a toner image, and thesample of the photoconductive layer was oil-desensitized under the sameconditions as described in *5) above. The printing plate thus preparedwas mounted on an offset printing machine (Oliver Model 52, manufacturedby Sakurai Seisakusho K.K.) as an offset master plate following byprinting. The number of prints obtained without causing backgroundstains in the non-image portions of prints and problems on the qualityof the image potions thereof was referred to as the printing durability.The larger the number of prints, the better the printing durability.

As can be seen from the results shown in Table 5, each of thelight-sensitive materials according to the present invention had goodsurface smoothness and mechanical strength of the photoconductive layer,and good electrostatic characteristics. The duplicated image formed wasclear and free from background fog in the non-image area. Those resultsappear to be due to sufficient adsorption of the binder resin onto thephotoconductive substance and sufficient covering of the surface of theparticles with the binder resin. For the same reason, when it was usedas an offset master plate precursor, oil-desensitization with anoil-desensitizing solution was sufficient to render the non-image areassatisfactorily hydrophilic, as shown by a small contact angle of 10° orless with water. On practical printing using the resulting printingplate, no background stains were observed in the prints.

In the light-sensitive material of the present invention using the resin(A') containing a methacrylate component having the specificsubstituent, the electrophotographic characteristics, particularly,photosensitivities of E_(1/10) and E_(1/100) were remarkably improved,as shown in Example 2.

Each sample of Comparative Examples A and B had a reduced DRR and anincreased E_(1/10). Further, under the conditions of high temperatureand high humidity, the tendency of degradation of DRR and E_(1/10) wasobserved. Moreover, the E_(1/100) value was further increased under suchconditions.

The value of E_(1/100) indicated an electrical potential remaining inthe non-image areas (exposed areas) after exposure at the practice ofimage formation. The smaller this value, the less the background stainsin the non-image areas. More specifically, it is requested that theremaining potential is decreased to -10 V or less. Therefore, an amountof exposure necessary to make the remaining potential below -10 V is animportant factor. In the scanning exposure system using a semiconductorlaser beam, it is quite important to make the remaining potential below-10 V by a small exposure amount in view of a design for an opticalsystem of a duplicator (such as cost of the device, and accuracy of theoptical system).

When each sample of Comparative Examples A and B was actually imagewiseexposed by a device of a small amount of exposure, the occurrence ofbackground fog in the non-image areas was observed particularly underhigh temperature and high humidity conditions.

Moreover, with respect to the contact angle with water when thelight-sensitive materials were subjected to the oil-desensitizingtreatment, each of the light-sensitive materials showed as small as 10degree or below which indicated that the surface of each sample wassufficiently rendered hydrophilic. However, when each printing plateprecursor obtained by plate making of the light-sensitive material wassubjected to the oil-desensitizing treatment to prepare a printing platefollowed by printing therewith, only the printing plate each formed fromthe light-sensitive materials according to the present invention canprovide 10,000 prints of clear image free from background stains. On thecontrary, in case of using the light-sensitive materials of ComparativeExamples A and B, background stains due to background fog on theprinting plate or due to edge mark of cutting of the original occurredin the non-image portions of the prints from the start of the printing.

From all these consideration, it is thus clear that theelectrophotographic light-sensitive material satisfying bothrequirements of electrostatic characteristics and printing suitabilitycan be obtained only in case of using the binder resin according to thepresent invention.

EXAMPLES 3 TO 19

Electrophotographic light-sensitive materials were prepared in the samemanner as described in Example 1, except for replacing Resin (A-2}andResin (B-1) with each of Resins (A) and (B) shown in Table 6 below,respectively.

The characteristics of the resulting light-sensitive materials wereevaluated in the same manner as described in Example 1. The resultsobtained are shown in Table 6 below. The electrostatic characteristicsin Table 6 are those determined under Condition II (30° C. and 80% RH).

                  TABLE 6                                                         ______________________________________                                                                           E.sub.1/10                                 Example                                                                              Resin   Resin   V.sub.10                                                                            DRR   (erg/ E.sub.1/100                          No.    (A)     (B)     (-V)  (%)   cm.sup.2)                                                                           (erg/cm.sup.2)                       ______________________________________                                         3     A-3     B-1     555   82    20    40                                    4     A-5     B-1     600   85    18    33                                    5     A-8     B-2     590   84    17    32                                    6     A-9     B-3     565   83    19    38                                    7     A-10    B-4     550   80    21    40                                    8     A-11    B-5     555   82    20    40                                    9     A-12    B-8     550   79    22    47                                   10     A-13    B-9     550   79    23    49                                   11     A-17    B-10    555   80    21    48                                   12     A-18    B-11    575   83    17    30                                   13     A-19    B-17    580   84    18    31                                   14     A-20    B-18    555   81    21    39                                   15     A-21    B-19    570   82    15    28                                   16     A-22    B-24    560   82    20    30                                   17     A-23    B-26    550   80    21    34                                   18     A-24    B-29    560   83    17    29                                   19     A-25    B-21    570   84    18    28                                   ______________________________________                                    

As is apparent from the results shown in Table 6, the excellentcharacteristics similar to those in Examples 1 and 2 are obtained.

Further, when these electrophotographic light-sensitive materials wereemployed as offset master plate precursors under the same printingcondition as described in Example 1, more than 10,000 good prints wereobtained respectively.

It can be seen from the results described above that each of thelight-sensitive materials according to the present invention wassatisfactory in all aspects of the surface smoothness and film strengthof the photoconductive layer, electrostatic characteristics, andprinting suitability.

EXAMPLES 20 TO 27

Electrophotographic light-sensitive materials were prepared in the samemanner as described in Example 1, except for replacing 6 g of Resin(A-2) with 6.5 g each of Resins (A) shown in Table 7 below, replacing 34g of Resin (B-1) with 33.5 g each of Resins (B) shown in Table 8 below,and replacing 0.018 g of Cyanine Dye (I) with 0.018 g of Cyanine Dye(II) shown below. ##STR133##

                  TABLE 7                                                         ______________________________________                                        Example No.     Resin (A) Resin (B)                                           ______________________________________                                        20              A-1       B-25                                                21              A-4       B-26                                                22              A-8       B-27                                                23              A-16      B-28                                                24              A-19      B-30                                                25              A-20      B-31                                                26              A-22      B-33                                                27              A-24      B-35                                                ______________________________________                                    

As the results of the evaluation same as described in Example 1, it canbe seen that each of the light-sensitive materials according to thepresent invention is excellent in charging properties, dark chargeretention rate, and photosensitivity, and provides a clear duplicatedimage free from background fog even when processed under severeconditions of high temperature and high humidity (30° C. and 80% RH).Further, when these materials were employed as offset master plateprecursors, more than 10,000 prints of clear images free from backgroundstains were obtained respectively.

EXAMPLE 28

A mixture of 6.5 g of Resin (A-1), 33.5 g of Resin (B-9), 200 g of zincoxide, 0.03 g of uranine, 0.075 g of Rose Bengale, 0.045 g ofbromophenol blue, 0.1 g of phthalic anhydride, and 240 g of toluene wasdispersed in a ball mill for 3 hours to prepare a coating compositionfor a light-sensitive layer. The coating composition was coated onpaper, which had been subjected to electrically conductive treatment, bya wire bar to a dry coverage of 20 g/m², followed by drying at 110° C.for 30 seconds. The coated material was allowed to stand in a dark placeat 20° C. and 65% RH for 24 hours to prepare an electrophotographiclight-sensitive material.

COMPARATIVE EXAMPLE C

An electrophotographic light-sensitive material was prepared in the samemanner as described in Example 28, except for using 33.5 g of Resin(R-1) described in Comparative Example A above in place of 33.5 g ofResin (B-9).

COMPARATIVE EXAMPLE D

An electrophotographic light-sensitive material was prepared in the samemanner as described in Example 28, except for using 33.5 g of Resin(R-2) described in Comparative Example B above in place of 33.5 g ofResin (B-9).

Each of the light-sensitive materials obtained in Example 28 andComparative Examples C and D was evaluated for film properties in termsof surface smoothness and mechanical strength; electrostaticcharacteristics; image forming performance; oil-desensitivity when usedas an offset master plate precursor (expressed in terms of contact angleof the layer with water after oil desensitization treatment); andprinting suitability (expressed in terms of background stain andprinting durability) according to the evaluation methods as described inExample 1, except that the electrostatic characteristics and imageforming performance were evaluated according to the following methods.

*7) Electrostatic Characteristics:

The light-sensitive material was charged by applying thereto coronadischarge of -6 kV for 20 seconds in a dark place under conditions of20° C. and 65% RH using a paper analyzer (Paper Analyzer Type SP-428,manufactured by Kawaguchi Denki K.K.). Ten seconds after the coronadischarge, the surface potential V₁₀ was measured. Then, the sample wasallowed to stand in a dark place for 60 seconds, and the potential V₇₀was measured. The dark decay retention rate (DRR (%)), i.e., percentretention of potential after decaying for 60 seconds in a dark place,was calculated from the following equation: DRR (%)=(V₇₀ /V₁₀)×100.

Also, the surface of the photoconductive layer was charged to -500 V bycorona discharge, then irradiated by visible light of 2.0 lux, and thetime required for decaying the surface potential (V₁₀) to 1/10 thereofwas measured thereby the exposure amount E_(1/10) (lux sec) wasobtained.

Further, the surface of the photoconductive layer was charged to -500 Vby corona discharge in the same manner as described for the measurementof E_(1/10), then irradiated by visible light of 2.0 lux, and the timerequired for decaying the surface potential (V₁₀) to 1/100 was measuredthereby the exposure amount E_(1/100) (lux.sec) was obtained.

The measurements were conducted under conditions of 20° C. and 65% RH(hereinafter referred to as Condition I) or 30° C. and 80% RH(hereinafter referred to as Condition II).

*8) Image Forming Performance:

The light-sensitive material was allowed to stand for one day underCondition I or II. Then, under each of Conditions I and II the samplewas treated using a full-automatic plate making machine (ELP 404V,manufactured by Fuji Photo Film Co., Ltd.) with a tone (ELP-T,manufactured by Fuji Photo Film Co., Ltd.). The duplicated image thusobtained was visually evaluated for fog and image quality. The originalused for the duplication was composed of letters by a word processor anda cutting of letters on straw paper pasted up thereon.

The results obtained are shown in Table 8 below.

                                      TABLE 8                                     __________________________________________________________________________                          Comparative                                                                            Comparative                                                    Example 28                                                                          Example C                                                                              Example D                                      __________________________________________________________________________    Surface Smoothness (sec/cc)                                                                   140   145      135                                            Film Strength (%)                                                                             97    87       91                                             Electrostatic Characteristics*.sup.7) :                                       V.sub.10 (-V):                                                                         Condition I                                                                          540   540      540                                                     Condition II                                                                         530   520      525                                            DRR (%): Condition I                                                                          96    93       94                                                      Condition II                                                                         95    88       92                                             E.sub.1/10 (lux · sec):                                                       Condition I                                                                          8.6   11.9     10.8                                                    Condition II                                                                         8.6   10.8     10.0                                           E.sub.1/100 (lux · sec):                                                      Condition I                                                                          10.0  26       20                                                      Condition II                                                                         11.5  30       27                                             Image-Forming Performance*.sup.8) :                                                    Condition I                                                                          Good  No Good  No Good                                                              (slight edge                                                                           (slight edge                                                         mark of  mark of                                                              cutting) cutting)                                                Condition II                                                                         Good  Poor     Poor                                                                 (edge mark of                                                                          (edge mark of                                                        cutting, slight                                                                        cutting, slight                                                      background fog)                                                                        background fog)                                Contact Angle   10 or less                                                                          10 or less                                                                             10 or less                                     With Water (°)                                                         Printing Durability:                                                                          10,000                                                                              Background                                                                             Background                                                     or more                                                                             stains from                                                                            stains from                                                          the start of                                                                           the start of                                                         printing printing                                       __________________________________________________________________________

As can be seen from the results shown in Table 8, the light-sensitivematerial according to the present invention had sufficient surfacesmoothness and mechanical strength of the photoconductive layer, andgood electrostatic characteristics which were hardly changed dependingon the fluctuation of environmental conditions. The duplicated imageobtained was clear and free from background fog.

On the contrary, each sample of Comparative Examples C and D wasinferior to the sample according to the present invention in itselectrostatic characteristics, particularly, in the fluctuations ofE_(1/100) value due to the change of environmental conditions. In theduplicated image formed therefrom, scraches of fine lines and backgroundfog were observed under the conditions of high temperature and highhumidity.

Furthermore, when each of the samples was used as an offset master plateprecursor, the samples of Comparative Examples C and D exhibitedbackground stains on the prints from the start of printing, while thesample of Example 28 according to the present invention could providemore than 10,000 prints of a clear image free from background stains.

From all these considerations, it is clear that only theelectrophotographic light-sensitive material according to the presentinvention is excellent in view of both smoothness and mechanicalstrength of photoconductive layer, electrostatic characteristics andprinting suitability.

EXAMPLES 29 TO 34

Electrophotographic light-sensitive materials were prepared in the samemanner as described in Example 28, except for replacing Resin (A-1) andResin (B-9) with each of 6.0 g of Resin (A}and 34.0 g of Resin (B) shownin Table 9 below, respectively.

                  TABLE 9                                                         ______________________________________                                        Example No.     Resin (A) Resin (B)                                           ______________________________________                                        29              A-2       B-14                                                30              A-7       B-19                                                31              A-8       B-21                                                32              A-14      B-23                                                33              A-26      B-27                                                34              A-27      B-35                                                ______________________________________                                    

As the results of the evaluation of each sample in the manner asdescribed above, it can be seen that each of the light-sensitivematerials according to the present invention is excellent in chargingproperties, dark charge retention rate, and photosensitivity, andprovides a clear duplicated image free from background fog and cut offine lines even when processed under severe conditions of hightemperature and high humidity (30° C. and 80% RH). Further, when thesematerials were employed as offset master plate precursors, more than10,000 prints of a clear image free from background stains were obtainedrespectively.

While the invention has been described in detail and with reference tospecific embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. An electrophotographic light-sensitive materialcomprising a support having provided thereon at least onephotoconductive layer containing an inorganic photoconductive substanceand a binder resin, wherein the binder resin comprises (A) at least oneresin (resin (A)) having a weight average molecular weight of from 1×10³to 2×10⁴ and containing not less than 30% by weight of a polymercomponent corresponding to a repeating unit represented by the generalformula (I) described below, and having at least one acidic groupselected from the group consisting of --PO₃ H₂, --SO₃ H, --COOH, --OH,##STR134## (wherein R represents a hydrocarbon group or --OR' (whereinR' represents a hydrocarbon group)) and a cyclic acidanhydride-containing group bonded to one of the terminals of the mainchain thereof; ##STR135## wherein a₁ and a₂ each represents a hydrogenatom, a halogen atom, a cyano group or a hydrocarbon group; and R₁represents a hydrocarbon group; and (B) at least one graft typecopolymer (resin (B)) having a weight average molecular weight of from3×10⁴ to 1×10⁶ and formed from, as a copolymerizable component, at leastone mono-functional macromonomer (M) having a weight average molecularweight of from 1×10³ to 2×10⁴ and comprising an AB block copolymer beingcomposed of an A block comprising at least one polymer componentcontaining at least one acidic group selected from --PO₃ H₂, --COOH,--SO₃ H, a phenolic hydroxy group, ##STR136## (wherein R represents ahydrocarbon group or --OR' (wherein R' represents a hydrocarbon group))and a cyclic acid anhydride-containing group, and a B block containingat least one polymer component represented by the general formula (II)described below and having a polymerizable double bond group bonded tothe terminal of the main chain of the B block polymer ##STR137## whereinb₁ and b₂ each represents a hydrogen atom, a halogen atom, a cyanogroup, a hydrocarbon group, --COOR₂₄ or --COOR₂₄ bonded via ahydrocarbon group (wherein R₂₄ represents a hydrocarbon group); X₁represents --COO--, --OCO--, --CH₂)_(l1) OCO--, --CH₂)_(l2) COO--(wherein l₁ and l₂ each represents an integer of from 1 to 3), --O--,--SO₂ --, --CO--, ##STR138## (wherein R₂₃ represents a hydrogen atom ora hydrocarbon group), --CONHCOO--, --CONHCONH--, or ##STR139## and R₂₁represents a hydrocarbon group, provided that when X₁ represents##STR140## R₂₁ represents a hydrogen atom or a hydrocarbon group.
 2. Anelectrophotographic light-sensitive material as claimed in claim 1,wherein the polymer component corresponding to the repeating unitrepresented by the general formula (I) is a methacrylate componentcorresponding to a repeating unit represented by the following generalformula (Ia) or (Ib): ##STR141## wherein A₁ and A₂ each represents ahydrogen atom, a hydrocarbon group having from 1 to 10 carbon atoms, achlorine atom, a bromine atom, --COD₁ or --COOD₂, wherein D₁ and D₂ eachrepresents a hydrocarbon group having from 1 to 10 carbon atoms; and B₁and B₂ each represents a mere bond or a linking group containing from 1to 4 linking atoms, which connects --COO-- and the benzene ring.
 3. Anelectrophotographic light-sensitive material as claimed in claim 2,wherein the linking group containing from 1 to 4 linking atomsrepresented by B₁ or B₂ is --CH₂ --_(n).sbsb.1 (n₁ represents an integerof 1, 2 or 3), --CH₂ OCO--, --CH₂ CH₂ OCO--, --CH₂ O--_(n).sbsb.2 (n₂represents an integer of 1 or 2), or --CH₂ CH₂ O--.
 4. Anelectrophotographic light-sensitive material as claimed in claim 2,wherein a content of the methacrylate component in the resin is from 50to 97% by weight.
 5. An electrophotographic light-sensitive material asclaimed in claim 1, wherein a content of the copolymer componentcorresponding to the repeating unit represented by the general formula(I) in the resin (A) is from 50 to 97% by weight.
 6. Anelectrophotographic light-sensitive material as claimed in claim 1,wherein the acidic group bonded to the terminal of the main chain of theresin (A) is selected from --PO₃ H₂ --SO₃ H, --COOH, ##STR142## whereinR represents a hydrocarbon group or OR' wherein R' represents ahydrocarbon group), and a cyclic acid anhydride-containing group.
 7. Anelectrophotographic light-sensitive material as claimed in claim 1,wherein the resin (A) further contains from 1 to 20% by weight of acopolymer component having a heat- and/or photocurable functional group.8. An electrophotographic light-sensitive material as claimed in claim1, wherein a content of the macromonomer (M) in the resin (B) is from 1to 60% by weight.
 9. An electrophotographic light-sensitive material asclaimed in claim 1, wherein the graft type copolymer contains themacromonomer (M) and a polymer component represented by the followinggeneral formula (III): ##STR143## wherein b₃ and b₄ each represents ahydrogen atom, a halogen atom, a cyano group, a hydrocarbon group,--COOR₂₄ ' or --COOR₂₄ ' bonded via a hydrocarbon group (wherein R₂₄ 'represents a hydrocarbon group); X₂ represents --COO--, --OCO--,--CH₂)_(l11) OCO--, --CH.sub.)_(l12) COO-- (wherein l₁₁ and l₁₂ eachrepresents an integer of from 1 to 3), --O--, --SO₂ --, --CO--,##STR144## (wherein R₂₃ ' represent a hydrogen atom or a hydrocarbongroup), --CONHCOO--, --CONHCONH--, or ##STR145## and R₂₂ represents ahydrocarbon group, provided that when X₁ represents ##STR146## R₂₂represents a hydrogen atom or a hydrocarbon group.
 10. Anelectrophotographic light-sensitive material as claimed in claim 9,wherein a ratio of the macromonomer (M) to a monomer corresponding tothe polymer component represented by the general formula (III) is from 1to 60/99 to 40 by weight.
 11. An electrophotographic light-sensitivematerial as claimed in claim 1, wherein the acidic group contained inthe A block of the macromonomer (M) is --COOH, --SO₃ H, a phenolichydroxyl group and ##STR147##
 12. An electrophotographic light-sensitivematerial as claimed in claim 1, wherein a ratio of the A block to the Bblock in the macromonomer (M) is from 1 to 30/99 to 70 by weight.
 13. Anelectrophotographic light-sensitive material as claimed in claim 1,wherein a ratio of the resin (A) to the resin (B) is from 5 to 50/95 to50 by weight.